id
int64 39
11.1M
| section
stringlengths 3
4.51M
| length
int64 2
49.9k
| title
stringlengths 1
182
| chunk_id
int64 0
68
|
|---|---|---|---|---|
1,967 |
# Apollo 12
## Mission highlights {#mission_highlights}
### Lunar orbit and Moon landing {#lunar_orbit_and_moon_landing}
Apollo 12 entered a lunar orbit of 170.2 by with an SPS burn of 352.25 seconds at mission time 83:25:26.36. On the first lunar orbit, there was a television transmission that resulted in good-quality video of the lunar surface. On the third lunar orbit, there was another burn to circularize the craft\'s orbit to 66.1 by, and on the next revolution, preparations began for the lunar landing. The CSM and LM undocked at 107:54:02.3; a half hour later there was a burn by the CSM to separate them. The 14.4 second burn by some of the CSM\'s thrusters meant that the two craft would be 2.2 nmi apart when the LM began the burn to move to a lower orbit in preparation for landing on the Moon.
The LM\'s Descent Propulsion System began a 29-second burn at 109:23:39.9 to move the craft to the lower orbit, from which the 717-second powered descent to the lunar surface began at 110:20:38.1. Conrad had trained to expect a pattern of craters known as \"the Snowman\" to be visible when the craft underwent \"pitchover\", with the Surveyor crater in its center, but had feared he would see nothing recognizable. He was astonished to see the Snowman right where it should be, meaning they were directly on course. He took over manual control, planning to land the LM, as he had in simulations, in an area near the Surveyor crater that had been dubbed \"Pete\'s Parking Lot\", but found it rougher than expected. He had to maneuver, and landed the LM at 110:32:36.2 (06:54:36 UTC on November 19, 1969), just 535 ft from the Surveyor probe. This achieved one objective of the mission, to perform a precision landing near the Surveyor craft.
The lunar coordinates of the landing site were 3.01239° S latitude, 23.42157° W longitude. The landing caused high velocity sandblasting of the Surveyor probe. It was later determined that the sandblasting removed more dust than it delivered onto the Surveyor, because the probe was covered by a thin layer that gave it a tan hue as observed by the astronauts, and every portion of the surface exposed to the direct sandblasting was lightened back toward the original white color through the removal of lunar dust.
| 386 |
Apollo 12
| 7 |
1,967 |
# Apollo 12
## Mission highlights {#mission_highlights}
### Lunar surface activities {#lunar_surface_activities}
When Conrad, the shortest man of the initial groups of astronauts, stepped onto the lunar surface his first words were \"Whoopie! Man, that may have been a small one for Neil, but that\'s a long one for me.\" This was not an off-the-cuff remark: Conrad had made a `{{USD|500}}`{=mediawiki} bet with reporter Oriana Fallaci he would say these words, after she had queried whether NASA had instructed Neil Armstrong what to say as he stepped onto the Moon. Conrad later said he was never able to collect the money.
thumb\|left\|upright=1.36\|Bean prepares to step onto the lunar surface.
To improve the quality of television pictures from the Moon, a color camera was carried on Apollo 12 (unlike the monochrome camera on Apollo 11). When Bean carried the camera to the place near the LM where it was to be set up, he inadvertently pointed it directly into the Sun, destroying the Secondary Electron Conduction (SEC) tube. Television coverage of this mission was thus terminated almost immediately.
After raising a U.S. flag on the Moon, Conrad and Bean devoted much of the remainder of the first EVA to deploying the Apollo Lunar Surface Experiments Package (ALSEP). There were minor difficulties with the deployment. Bean had trouble extracting the RTG\'s plutonium fuel element from its protective cask, and the astronauts had to resort to the use of a hammer to hit the cask and dislodge the fuel element. Some of the ALSEP packages proved hard to deploy, though the astronauts were successful in all cases. With the PSE able to detect their footprints as they headed back to the LM, the astronauts secured a core tube full of lunar material, and collected other samples. The first EVA lasted 3 hours, 56 minutes and 3 seconds.
Four possible geologic traverses had been planned, the variable being where the LM might set down. Conrad had landed it between two of these potential landing points, and during the first EVA and the rest break that followed, scientists in Houston combined two of the traverses into one that Conrad and Bean could follow from their landing point. The resultant traverse resembled a rough circle, and when the astronauts emerged from the LM some 13 hours after ending the first EVA, the first stop was Head crater, some 100 yard from the LM. There, Bean noticed that Conrad\'s footprints showed lighter material underneath, indicating the presence of ejecta from Copernicus crater, 230 mi to the north, something that scientists examining overhead photographs of the site had hoped to find. After the mission, samples from Head allowed geologists to date the impact that formed Copernicus---according to initial dating, some 810,000,000 years ago.
thumb\|upright=1.3\|right\|Conrad with the U.S. flag
The astronauts proceeded to Bench crater and Sharp crater and past Halo crater before arriving at Surveyor crater, where the Surveyor 3 probe had landed. Fearing treacherous footing or that the probe might topple on them, they approached Surveyor cautiously, descending into the shallow crater some distance away and then following a contour to reach the craft, but found the footing solid and the probe stable. They collected several pieces of Surveyor, including the television camera, as well as taking rocks that had been studied by television. Conrad and Bean had procured an automatic timer for their Hasselblad cameras, and had brought it with them without telling Mission Control, hoping to take a selfie of the two of them with the probe, but when the time came to use it, could not locate it among the lunar samples they had already placed in their Hand Tool Carrier. Before returning to the LM\'s vicinity, Conrad and Bean went to Block crater, within Surveyor crater. The second EVA lasted 3 hours, 49 minutes, 15 seconds, during which they traveled 4300 ft. During the EVAs, Conrad and Bean went as far as 1350 ft from the LM, and collected 73.75 lb of samples.
### Lunar orbit solo activities {#lunar_orbit_solo_activities}
After the LM\'s departure, Gordon had little to say as Mission Control focused on the lunar landing. Once that was accomplished, Gordon sent his congratulations and, on the next orbit, was able to spot both the LM and the Surveyor on the ground and convey their locations to Houston. During the first EVA, Gordon prepared for a plane change maneuver, a burn to alter the CSM\'s orbit to compensate for the rotation of the Moon, though at times he had difficulty communicating with Houston since Conrad and Bean were using the same communications circuit. Once the two moonwalkers had returned to the LM, Gordon executed the burn, which ensured he would be in the proper position to rendezvous with the LM when it launched from the Moon.
While alone in orbit, Gordon performed the Lunar Multispectral Photography Experiment, using four Hasselblad cameras arranged in a ring and aimed through one of the CM\'s windows. With each camera having a different color filter, simultaneous photos would be taken by each, showing the appearance of lunar features at different points on the spectrum. Analysis of the images might reveal colors not visible to the naked eye or detectable with ordinary color film, and information could be obtained about the composition of sites that would not soon be visited by humans. Among the sites studied were contemplated landing points for future Apollo missions.
### Return
LM *Intrepid* lifted off from the Moon at mission time 143:03:47.78, or 14:25:47 UTC on November 20, 1969; after several maneuvers, CSM and LM docked three and a half hours later. At 147:59:31.6, the LM ascent stage was jettisoned, and shortly thereafter the CSM maneuvered away. Under control from Earth, the LM\'s remaining propellant was depleted in a burn that caused it to impact the Moon 39 nmi from the Apollo 12 landing point. The seismometer the astronauts had left on the lunar surface registered the resulting vibrations for more than an hour.
The crew stayed another day in lunar orbit taking photographs of the surface, including of candidate sites for future Apollo landings. A second plane change maneuver was made at 159:04:45.47, lasting 19.25 seconds.
The trans-Earth injection burn, to send the CSM *Yankee Clipper* towards home, was conducted at 172:27:16.81 and lasted 130.32 seconds. Two short midcourse correction burns were made en route. A final television broadcast was made, the astronauts answering questions submitted by the media. There was ample time for rest on the way back to Earth. One event was the photography of a solar eclipse that occurred when the Earth came between the spacecraft and the Sun; Bean described it as the most spectacular sight of the mission.
| 1,111 |
Apollo 12
| 8 |
1,967 |
# Apollo 12
## Mission highlights {#mission_highlights}
### Splashdown
*Yankee Clipper* returned to Earth on November 24, 1969, splashing down in the South Pacific Ocean southeast of Samoa at 244:36:25 (20:58:24 UTC, 10:58:24 am HST, local time at the landing site). The landing was hard, resulting in a camera becoming dislodged and striking Bean in the forehead. After recovery by `{{USS|Hornet|CV-12|6}}`{=mediawiki}, they entered the Mobile Quarantine Facility (MQF), while lunar samples and Surveyor parts were sent ahead by air to the Lunar Receiving Laboratory (LRL) in Houston. Once the *Hornet* docked in Hawaii, the MQF was offloaded and flown to Ellington Air Force Base near Houston on November 29, from where it was taken to the LRL, where the astronauts remained until released from quarantine on December 10.
## Mission insignia {#mission_insignia}
frameless\|left\|upright=0.8
The Apollo 12 mission patch shows the crew\'s naval background; all three astronauts at the time of the mission were U.S. Navy commanders. It features a clipper ship arriving at the Moon, representing the CM *Yankee Clipper*. The ship trails fire, and flies the flag of the United States. The mission name APOLLO XII and the crew names are on a wide gold border, with a small blue trim. Blue and gold are traditional U.S. Navy colors. The patch has four stars on it -- one each for the three astronauts who flew the mission and one for Clifton Williams, the original LMP on Conrad\'s crew who was killed in 1967 and would have flown the mission. The star was placed there at the suggestion of his replacement, Bean.
The insignia was designed by the crew with the aid of several employees of NASA contractors. The Apollo 12 landing area on the Moon is within the portion of the lunar surface shown on the insignia, based on a photograph of a globe of the Moon, taken by engineers. The clipper ship was based on photographs of such a ship obtained by Bean.
| 325 |
Apollo 12
| 9 |
1,967 |
# Apollo 12
## Aftermath and spacecraft location {#aftermath_and_spacecraft_location}
thumb\|upright=1.3\|right\|Apollo 12 CM *Yankee Clipper* on display at the Virginia Air and Space Center in Hampton, Virginia
After the mission, Conrad urged his crewmates to join him in the Skylab program, seeing in it the best chance of flying in space again. Bean did so---Conrad commanded Skylab 2, the first crewed mission to the space station, while Bean commanded Skylab 3. Gordon, though, still hoped to walk on the Moon and remained with the Apollo program, serving as backup commander of Apollo 15. He was the likely commander of Apollo 18, but that mission was canceled and he did not fly in space again.
The Apollo 12 command module *Yankee Clipper*, was displayed at the Paris Air Show and was then placed at NASA\'s Langley Research Center in Hampton, Virginia; ownership was transferred to the Smithsonian in July 1971. It is on display at the Virginia Air and Space Center in Hampton.
Mission Control had remotely fired the service module\'s thrusters after jettison, hoping to have it skip off the atmosphere and enter a high-apogee orbit, but the lack of tracking data confirming this caused it to conclude it most likely burned up in the atmosphere at the time of CM re-entry. The S-IVB is in a solar orbit that is sometimes affected by the Earth.
The ascent stage of LM *Intrepid* impacted the Moon November 20, 1969, at 22:17:17.7 UT (5:17 pm EST)`{{spaces}}`{=mediawiki}3.94 S 21.20 W type:event_globe:moon name=Apollo 12 Intrepid lunar module impact. In 2009, the Lunar Reconnaissance Orbiter (LRO) photographed the Apollo 12 landing site, where the descent stage, ALSEP, Surveyor 3 spacecraft, and astronaut footpaths remain. In 2011, the LRO returned to the landing site at a lower altitude to take higher resolution photographs
| 296 |
Apollo 12
| 10 |
1,969 |
# Apollo 15
**Apollo 15** (July 26`{{snd}}`{=mediawiki}August 7, 1971) was the ninth crewed mission in the Apollo program and the fourth Moon landing. It was the first J mission, with a longer stay on the Moon and a greater focus on science than earlier landings. Apollo 15 saw the first use of the Lunar Roving Vehicle.
The mission began on July 26 and ended on August 7, with the lunar surface exploration taking place between July 30 and August 2. Commander David Scott and Lunar Module Pilot James Irwin landed near Hadley Rille and explored the local area using the rover, allowing them to travel further from the Lunar Module than had been possible on previous missions. They spent 18`{{frac|1|2}}`{=mediawiki} hours on the Moon\'s surface on four extravehicular activities (EVA), and collected 77 kg of surface material.
At the same time, Command Module Pilot Alfred Worden orbited the Moon, operating the sensors in the scientific instrument module (SIM) bay of the service module. This suite of instruments collected data on the Moon and its environment using a panoramic camera, a gamma-ray spectrometer, a mapping camera, a laser altimeter, a mass spectrometer, and a lunar subsatellite deployed at the end of the moonwalks. The Lunar Module returned safely to the command module and, at the end of Apollo 15\'s 74th lunar orbit, the engine was fired for the journey home. During the return trip, Worden performed the first spacewalk in deep space. The Apollo 15 mission splashed down safely on August 7 despite the partial opening of one of its three parachutes.
The mission accomplished its goals and also saw the collection of the Genesis Rock, thought to be part of the Moon\'s early crust, and Scott\'s use of a hammer and a feather to validate Galileo\'s theory that when there is no air resistance, objects fall at the same rate due to gravity regardless of their mass. The mission received negative publicity the following year when it emerged that the crew had carried unauthorized postal covers to the lunar surface, some of which were sold by a West German stamp dealer. The members of the crew were reprimanded for poor judgment, and did not fly in space again.
## Background
In 1962, NASA contracted for the construction of fifteen Saturn V rockets to achieve the Apollo program\'s goal of a crewed landing on the Moon by 1970; at the time no one knew how many missions this would require. In 1969 Apollo 11 succeeded in landing on the Moon with the sixth Saturn V, so nine rockets remained available for a hoped-for total of ten landings. These plans included a heavier, extended version of the Apollo spacecraft to be used in the last five missions (Apollo 16 through 20). The revamped Lunar Module would be capable of up to a 75-hour stay, and would carry a Lunar Roving Vehicle to the Moon\'s surface. The service module would house a package of orbital experiments to gather data on the Moon. In the original plan Apollo 15 was to be the last of the non-extended missions to land in Censorinus crater. But in anticipation of budget cuts, NASA cancelled three landing missions by September 1970. Apollo 15 became the first of three extended missions, known as J missions, and the landing site was moved to Hadley Rille, originally planned for Apollo 19.
| 560 |
Apollo 15
| 0 |
1,969 |
# Apollo 15
## Crew and key Mission Control personnel {#crew_and_key_mission_control_personnel}
### Crew
Scott was born in 1932 in San Antonio, Texas, and, after spending his freshman year at the University of Michigan on a swimming scholarship, transferred to the United States Military Academy, from which he graduated in 1954. Serving in the Air Force, Scott had received two advanced degrees from MIT in 1962 before being selected as one of the third group of astronauts the following year. He flew in Gemini 8 in 1966 alongside Neil Armstrong and as command module pilot of Apollo 9 in 1969. Worden was born in 1932 in Jackson, Michigan, and like his commander, had attended West Point (class of 1955) and served in the Air Force. Worden earned two master\'s degrees in engineering from Michigan in 1963. Irwin had been born in 1930 in Pittsburgh, and had attended the United States Naval Academy, graduating in 1951 and serving in the Air Force, receiving a master\'s degree from Michigan in 1957. Both Worden and Irwin were selected in the fifth group of astronauts (1966), and Apollo 15 would be their only spaceflight. All three future astronauts had attended Michigan, and two had taken degrees from there; it had been the first university to offer an aeronautical engineering program.
The backup crew was Richard F. Gordon Jr. as commander, Vance D. Brand as command module pilot and Harrison H. Schmitt as Lunar Module pilot. By the usual rotation of crews, the three would most likely have flown Apollo 18, which was canceled. Brand flew later on the Apollo--Soyuz Test Project and on STS-5, the first operational Space Shuttle mission. With NASA under intense pressure to send a professional scientist to the Moon, Schmitt, a geologist, was selected as LMP of Apollo 17 instead of Joe Engle. Apollo 15\'s support crew consisted of astronauts Joseph P. Allen, Robert A. Parker and Karl G. Henize. All three were scientist-astronauts, selected in 1967, as the prime crew felt they needed more assistance with the science than with the piloting. None of the support crew would fly during the Apollo program, waiting until the Space Shuttle program to go into space.
### Mission Control {#mission_control}
The flight directors for Apollo 15 were as follows:
- Gerry Griffin, Gold team
- Milton Windler, Maroon team
- Glynn Lunney, Black team
- Gene Kranz, White team
During a mission the capsule communicators (CAPCOMs), always fellow astronauts, were the only people who normally would speak to the crew. For Apollo 15, the CAPCOMs were Allen, Brand, C. Gordon Fullerton, Gordon, Henize, Edgar D. Mitchell, Parker, Schmitt and Alan B. Shepard.
| 439 |
Apollo 15
| 1 |
1,969 |
# Apollo 15
## Planning and training {#planning_and_training}
Schmitt and other scientist-astronauts advocated for a greater place for science on the early Apollo missions. They were often met with disinterest from other astronauts, or found science displaced by higher priorities. Schmitt realized that what was needed was an expert teacher who could fire the astronauts\' enthusiasm, and contacted Caltech geologist Lee Silver, whom Schmitt introduced to Apollo 13\'s commander, Jim Lovell, and to its Lunar Module pilot, Fred Haise, then in training for their mission. Lovell and Haise were willing to go on a field expedition with Silver, and geology became a significant part of their training. Geologist Farouk El-Baz trained the prime crew\'s command module pilot, Ken Mattingly to inform his planned observations from lunar orbit. The crew\'s newly acquired skills mostly went unused, due to the explosion that damaged the Apollo 13 spacecraft, and caused an abort of the mission. Apollo 14\'s CMP, Stuart Roosa, was enthusiastic about geology, but the mission commander, Shepard, less so.
Already familiar with the spacecraft as the backup crew for Apollo 12, Scott, Worden and Irwin could devote more of their training time as prime crew for Apollo 15 to geology and sampling techniques. Scott was determined that his crew bring back the maximum amount of scientific data possible, and met with Silver in April 1970 to begin planning the geological training. Schmitt\'s assignment as Apollo 15\'s backup LMP made him an insider, and allowed him to spark competition between the prime and backup crews. The cancellation of two Apollo missions in September 1970 transformed Apollo 15 into a J mission, with a longer stay on the lunar surface, and the first Lunar Roving Vehicle (LRV). This change was welcomed by Scott, who according to David West Reynolds in his account of the Apollo program, was \"something more than a hotshot pilot. Scott had the spirit of a true explorer\", one determined to get the most from the J mission. The additional need for communications, including from planned experiments and the rover, required the near-rebuilding of the Honeysuckle Creek Tracking Station in Australia.
Geology field trips took place about once a month throughout the crew\'s 20 months of training. At first, Silver would take the commanders and LMPs from the prime and backup crews to geological sites in Arizona and New Mexico as if for a normal field geology lesson, but closer to launch, these trips became more realistic. Crews began to wear mock-ups of the backpacks they would carry while hiking near the Rio Grande Gorge, and communicate using walkie-talkies to a CAPCOM in a tent. The CAPCOM was accompanied by a geologist unfamiliar with the area who would rely on the astronauts\' descriptions to interpret the findings, and familiarized the crew members with describing landscapes to people who could not see them. Considering himself a serious amateur, Scott came to enjoy field geology.
The decision to land at Hadley came in September 1970. The Site Selection Committee had narrowed the field down to two sites---Hadley Rille, a deep channel on the edge of Mare Imbrium close to the Apennine mountains or the crater Marius, near which were a group of low, possibly volcanic, domes. Although not ultimately his decision, the commander of a mission always held great sway. To David Scott the choice was clear, as Hadley \"had more variety. There is a certain intangible quality which drives the spirit of exploration and I felt that Hadley had it. Besides it looked beautiful and usually when things look good they are good.\" The selection of Hadley was made although NASA lacked high resolution images of the landing site; none had been made as the site was considered too rough to risk one of the earlier Apollo missions. The proximity of the Apennine mountains to the Hadley site required a landing approach trajectory of 26 degrees, far steeper than the 15 degrees in earlier Apollo landings.
The expanded mission meant that Worden spent much of his time at North American Rockwell\'s facilities at Downey, California, where the command and service module (CSM) was being built. He undertook a different kind of geology training. Working with El-Baz, he studied maps and photographs of the craters he would pass over while orbiting alone in the CSM. As El-Baz listened and gave feedback, Worden learned how to describe lunar features in a way that would be useful to the scientists who would listen to his transmissions back on Earth. Worden found El-Baz to be an enjoyable and inspiring teacher. Worden usually accompanied his crewmates on their geology field trips, though he was often in an airplane overhead, describing features of the landscape as the plane simulated the speed at which the lunar landscape would pass below the CSM.
The demands of the training strained both Worden\'s and Irwin\'s marriages; each sought Scott\'s advice, fearing a divorce might endanger their places on the mission as not projecting the image NASA wanted for the astronauts. Scott consulted Director of Flight Crew Operations Deke Slayton, their boss, who stated what was important was that the astronauts do their jobs. Although the Irwins overcame their marital difficulties, the Wordens divorced before the mission.
| 865 |
Apollo 15
| 2 |
1,969 |
# Apollo 15
## Hardware
### Spacecraft
Apollo 15 used command and service module CSM-112, which was given the call sign *Endeavour*, named after HMS *Endeavour*, and Lunar Module LM-10, call sign *Falcon*, named after the United States Air Force Academy mascot. Scott explained the choice of the name *Endeavour* on the grounds that its captain, James Cook, had commanded the first purely scientific sea voyage, and Apollo 15 was the first lunar landing mission on which there was a heavy emphasis on science. Apollo 15 took with it a small piece of wood from Cook\'s ship, while *Falcon* carried two falcon feathers to the Moon in recognition of the crew\'s service in the Air Force. Also part of the spacecraft were a Launch Escape System and a Spacecraft-Lunar Module Adapter, numbered SLA-19.
Technicians at the Kennedy Space Center had some problems with the instruments in the service module\'s scientific instrument module (SIM) bay. Some instruments were late in arriving, and principal investigators or representatives of NASA contractors sought further testing or to make small changes. Mechanical problems came from the fact the instruments were designed to operate in space, but had to be tested on the surface of the Earth. As such, things like the 7.5 m (24 ft) booms for the mass and gamma ray spectrometers could be tested only using equipment that tried to mimic the space environment, and, in space, the mass spectrometer boom several times did not fully retract.
On the Lunar Module, the fuel and oxidizer tanks were enlarged on both the descent and ascent stages, and the engine bell on the descent stage was extended. Batteries and solar cells were added for increased electrical power. In all this increased the weight of the Lunar Module to 36000 lb, 4000 lb heavier than previous models.
If Apollo 15 had flown as an H mission, it would have been with CSM-111 and LM-9. That CSM was used by the Apollo--Soyuz Test Project in 1975, but the lunar module went unused and is now at the Kennedy Space Center Visitor Complex. *Endeavour* is on display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio, following its transfer of ownership from NASA to the Smithsonian in December 1974.
### Launch vehicle {#launch_vehicle}
The Saturn V that launched Apollo 15 was designated SA-510, the tenth flight-ready model of the rocket. As the payload of the rocket was greater, changes were made to the rocket and to its launch trajectory. It was launched in a more southerly direction (80--100 degrees azimuth) than previous missions, and the Earth parking orbit was lowered to 166 km. These two changes meant 1100 lb more could be launched. The propellant reserves were reduced and the number of retrorockets on the S-IC first stage (used to separate the spent first stage from the S-II second stage) reduced from eight to four. The four outboard engines of the S-IC would be burned longer and the center engine would also burn longer. Changes were also made to the S-II to dampen pogo oscillations.
Once all major systems were installed in the Saturn V, it was moved from the Vehicle Assembly Building to the launch site, Launch Complex 39A. During late June and early July 1971, the rocket and Launch Umbilical Tower (LUT) were struck by lightning at least four times. There was no damage to the vehicle, and only minor damage to ground support equipment.
### Space suits {#space_suits}
The Apollo 15 astronauts wore redesigned space suits. On all previous Apollo flights, including the non-lunar flights, the commander and lunar module pilot had worn suits with the life support, liquid cooling, and communications connections in two parallel rows of three. On Apollo 15, the new suits, dubbed the \"A7LB\", had the connectors situated in triangular pairs. This new arrangement, along with the relocation of the entry zipper (which went in an up-down motion on the old suits), to run diagonally from the right shoulder to the left hip, aided in suiting and unsuiting in the cramped confines of the spacecraft. It also allowed for a new waist joint, letting the astronauts bend completely over, and sit on the rover. Upgraded backpacks allowed for longer-duration moonwalks. As in all missions from and after Apollo 13, the commander\'s suit bore a red stripe on the helmet, arms and legs.
Worden wore a suit similar to those worn by the Apollo 14 astronauts, but modified to interface with Apollo 15\'s equipment. Gear needed only for lunar surface EVAs, such as the liquid cooling garment, was not included with Worden\'s suit, as the only EVA he was expected to do was one to retrieve film cartridges from the SIM bay on the flight home.
| 793 |
Apollo 15
| 3 |
1,969 |
# Apollo 15
## Hardware
### Lunar Roving Vehicle {#lunar_roving_vehicle}
thumb\|upright=1.49\|right\|alt=Astronaut works on the Moon at the lunar rover\|Irwin with the Lunar Roving Vehicle on the Moon. Mons Hadley is in the background. *Main article: Lunar Roving Vehicle*
A vehicle that could operate on the surface of the Moon had been considered by NASA since the early 1960s. An early version was called MOLAB, which had a closed cabin and would have massed about 6000 lb; some scaled-down prototypes were tested in Arizona. As it became clear NASA would not soon establish a lunar base, such a large vehicle seemed unnecessary. Still, a rover would enhance the J missions, which were to concentrate on science, though its mass was limited to about 500 lb and it was not then clear that so light a vehicle could be useful. NASA did not decide to proceed with a rover until May 1969, as Apollo 10, the dress rehearsal for the Moon landing, made its way home from lunar orbit. Boeing received the contract for three rovers on a cost-plus basis; overruns (especially in the navigation system) meant the three vehicles eventually cost a total of \$40 million. These cost overruns gained considerable media attention at a time of greater public weariness with the space program, when NASA\'s budget was being cut.
The Lunar Roving Vehicle could be folded into a space 5 ft by 20 in (1.5 m by 0.5 m). Unloaded, it weighed 460 lb (209 kg) and when carrying two astronauts and their equipment, 1500 lb (700 kg). Each wheel was independently driven by a `{{frac|1|4}}`{=mediawiki} horsepower (200 W) electric motor. Although it could be driven by either astronaut, the commander always drove. Travelling at speeds up to 6 to 8 mph (10 to 12 km/h), astronauts for the first time could travel far afield from their lander and still have enough time to do some scientific experiments. The Apollo 15 rover bore a plaque, reading: \"Man\'s First Wheels on the Moon, Delivered by Falcon, July 30, 1971\". During pre-launch testing, the LRV was given additional bracing, lest it collapse if someone sat on it under Earth conditions.
| 358 |
Apollo 15
| 4 |
1,969 |
# Apollo 15
## Hardware
### Particles and Fields Subsatellite {#particles_and_fields_subsatellite}
The Apollo 15 Particles and Fields Subsatellite (PFS-1) was a small satellite released into lunar orbit from the SIM bay just before the mission left orbit to return to Earth. Its main objectives were to study the plasma, particle, and magnetic field environment of the Moon and map the lunar gravity field. Specifically, it measured plasma and energetic particle intensities and vector magnetic fields, and facilitated tracking of the satellite velocity to high precision. A basic requirement was that the satellite acquire fields and particle data everywhere on the orbit around the Moon. As well as measuring magnetic fields, the satellite contained sensors to study the Moon\'s mass concentrations, or mascons. The satellite orbited the Moon and returned data from August 4, 1971, until January 1973, when, following multiple failures of the subsatellite\'s electronics, ground support was terminated. It is believed to have crashed into the Moon sometime thereafter.
| 160 |
Apollo 15
| 5 |
1,969 |
# Apollo 15
## Mission highlights {#mission_highlights}
### Launch and outbound trip {#launch_and_outbound_trip}
*Main article: Journey of Apollo 15 to the Moon*
Apollo 15 was launched on July 26, 1971, at 9:34 am EDT from the Kennedy Space Center at Merritt Island, Florida. The time of launch was at the very start of the two-hour, 37-minute launch window, which would allow Apollo 15 to arrive at the Moon with the proper lighting conditions at Hadley Rille; had the mission been postponed beyond another window on July 27, it could not have been rescheduled until late August. The astronauts had been awakened five and a quarter hours before launch by Slayton, and after breakfast and suiting up, had been taken to Pad 39A, launch site of all seven attempts at crewed lunar landing, and entered the spacecraft about three hours before launch. There were no unplanned delays in the countdown.
At 000:11:36 into the mission, the S-IVB engine shut down, leaving Apollo 15 in its planned parking orbit in low Earth orbit. The mission remained there for 2 hours and 40 minutes, allowing the crew (and Houston, via telemetry) to check the spacecraft\'s systems. At 002:50.02.6 into the mission, the S-IVB was restarted for trans-lunar injection (TLI), placing the craft on a path to the Moon. Before TLI, the craft had completed 1.5 orbits around the Earth.
The command and service module (CSM) and the Lunar Module remained attached to the nearly-exhausted S-IVB booster. Once trans-lunar injection had been achieved, placing the spacecraft on a trajectory towards the Moon, explosive cords separated the CSM from the booster as Worden operated the CSM\'s thrusters to push it away. Worden then maneuvered the CSM to dock with the LM (mounted on the end of the S-IVB), and the combined craft was then separated from the S-IVB by explosives. After Apollo 15 separated from the booster, the S-IVB maneuvered away, and, as planned, impacted the Moon about an hour after the crewed spacecraft entered lunar orbit, though due to an error the impact was 146 km away from the intended target. The booster\'s impact was detected by the seismometers left on the Moon by Apollo 12 and Apollo 14, providing useful scientific data.
There was a malfunctioning light on the craft\'s service propulsion system (SPS); after considerable troubleshooting, the astronauts did a test burn of the system that also served as a midcourse correction. This occurred about 028:40:00 into the mission. Fearing that the light meant the SPS might unexpectedly fire, the astronauts avoided using the control bank with the faulty light, bringing it online only for major burns, and controlling it manually. After the mission returned, the malfunction proved to be caused by a tiny bit of wire trapped within the switch.
After purging and renewing the LM\'s atmosphere to eliminate any contamination, the astronauts entered the LM about 34 hours into the mission, needing to check the condition of its equipment and move in items that would be required on the Moon. Much of this work was televised back to Earth, the camera operated by Worden. The crew discovered a broken outer cover on the Range/Range Rate tapemeter. This was a concern not only because an important piece of equipment, providing information on distance and rate of approach, might not work properly, but because bits of the glass cover were floating around *Falcon*{{\'s}} interior. The tapemeter was supposed to be in a helium atmosphere, but due to the breakage, it was in the LM\'s oxygen atmosphere. Testing on the ground verified the tapemeter would still work properly, and the crew removed most of the glass using a vacuum cleaner and adhesive tape.
As yet, there had been only minor problems, but at about 61:15:00 mission time (the evening of July 28 in Houston), Scott discovered a leak in the water system while preparing to chlorinate the water supply. The crew could not tell where it was coming from, and the issue had the potential to become serious. The experts in Houston found a solution, which was successfully implemented by the crew. The water was mopped up with towels, which were then put out to dry in the tunnel between the command module (CM) and Lunar Module---Scott stated it looked like someone\'s laundry.
At 073:31:14 into the mission, a second midcourse correction, with less than a second of burn, was made. Although there were four opportunities to make midcourse corrections following TLI, only two were needed. Apollo 15 approached the Moon on July 29, and the lunar orbit insertion (LOI) burn had to be made using the SPS, on the far side of the Moon, out of radio contact with Earth. If no burn occurred, Apollo 15 would emerge from the lunar shadow and come back in radio contact faster than expected; the continued lack of communication allowed Mission Control to conclude that the burn had taken place. When contact resumed, Scott did not immediately give the particulars of the burn, but spoke admiringly of the beauty of the Moon, causing Alan Shepard, the Apollo 14 commander, who was awaiting a television interview, to grumble, \"To hell with that shit, give us details of the burn.\" The 398.36-second burn took place at 078:31:46.7 into the mission at an altitude of 86.7 nmi above the Moon, and placed Apollo 15 in an elliptical lunar orbit of 170.1 by.
| 894 |
Apollo 15
| 6 |
1,969 |
# Apollo 15
## Mission highlights {#mission_highlights}
### Lunar orbit and landing {#lunar_orbit_and_landing}
thumb\|upright=1.2\|alt=Control panel of lunar lander\|The interior of *Falcon* thumb\|upright=1.2\|The Apollo 15 command and service module in lunar orbit, photographed from *Falcon* On Apollo 11 and 12, the Lunar Module decoupled from the CSM and was piloted to a much lower orbit from which the lunar landing attempt commenced; to save fuel in an increasingly heavy lander, beginning with Apollo 14, the SPS in the service module made that burn, known as descent orbit insertion (DOI), with the lunar module still attached to the CSM. The initial orbit Apollo 15 was in had its apocynthion, or high point, over the landing site at Hadley; a burn at the opposite point in the orbit was performed, with the result that Hadley would now be under the craft\'s pericynthion, or low point. The DOI burn was performed at 082:39:49.09 and took 24.53 seconds; the result was an orbit with apocynthion of 58.5 nmi and pericynthion of 9.6 nmi. Overnight between July 29 and 30, as the crew rested, it became apparent to Mission Control that mass concentrations in the Moon were making Apollo 15\'s orbit increasingly elliptical---pericynthion was 7.6 nmi by the time the crew was awakened on July 30. This, and uncertainty as to the exact altitude of the landing site, made it desirable that the orbit be modified, or trimmed. Using the craft\'s RCS thrusters, this took place at 095:56:44.70, lasting 30.40 seconds, and raised the pericynthion to 8.8 nmi and the apocynthion to 60.2 nmi.
As well as preparing the Lunar Module for its descent, the crew continued observations of the Moon (including of the landing site at Hadley) and provided television footage of the surface. Then, Scott and Irwin entered the Lunar Module in preparation for the landing attempt. Undocking was planned for 100:13:56, over the far side of the Moon, but nothing happened when separation was attempted. After analyzing the problem, the crew and Houston decided the probe instrumentation umbilical was likely loose or disconnected; Worden went into the tunnel connecting the command and lunar modules and determined this was so, seating it more firmly. With the problem resolved, *Falcon* separated from *Endeavour* at 100:39:16.2, about 25 minutes late, at an altitude of 5.8 nmi. Worden in *Endeavour* executed a SPS burn at 101:38:58.98 to send *Endeavour* to an orbit of 65.2 nmi by 54.8 nmi in preparation for his scientific work.
Aboard *Falcon*, Scott and Irwin prepared for powered descent initiation (PDI), the burn that was to place them on the lunar surface, and, after Mission Control gave them permission, they initiated PDI at 104:30:09.4 at an altitude of 5.8 nmi, slightly higher than planned. During the first part of the descent, *Falcon* was aligned so the astronauts were on their backs and thus could not see the lunar surface below them, but after the craft made a pitchover maneuver, they were upright and could see the surface in front of them. Scott, who as commander performed the landing, was confronted with a landscape that did not at first seem to resemble what he had seen during simulations. Part of this was due to an error in the landing path of some 3000 ft, of which CAPCOM Ed Mitchell informed the crew prior to pitchover; part because the craters Scott had relied on in the simulator were difficult to make out under lunar conditions, and he initially could not see Hadley Rille. He concluded that they were likely to overshoot the planned landing site, and, once he could see the rille, started maneuvering the vehicle to move the computer\'s landing target back towards the planned spot, and looked for a relatively smooth place to land.
thumb\|upright=1.2\|alt=Film showing the lunar surface as the lander descends to it\|Apollo 15 landing on the Moon at Hadley, seen from the perspective of the Lunar Module Pilot. Starts at about 5000 feet. Below about 60 ft, Scott could see nothing of the surface because of the quantities of lunar dust being displaced by *Falcon*{{\'s}} exhaust. *Falcon* had a larger engine bell than previous LMs, in part to accommodate a heavier load, and the importance of shutting down the engine at initial contact rather than risk \"blowback\", the exhaust reflecting off the lunar surface and going back into the engine (possibly causing an explosion) had been impressed on the astronauts by mission planners. Thus, when Irwin called \"Contact\", indicating that one of the probes on the landing leg extensions had touched the surface, Scott immediately shut off the engine, letting the lander fall the remaining distance to the surface. Already moving downward at about .5 ft per second, *Falcon* dropped from a height of 1.6 ft. Scott\'s speed resulted in what was likely the hardest lunar landing of any of the crewed missions, at about 6.8 ft per second, causing a startled Irwin to yell \"Bam!\" Scott had landed *Falcon* on the rim of a small crater he could not see, and the lander settled back at an angle of 6.9 degrees and to the left of 8.6 degrees. Irwin described it in his autobiography as the hardest landing he had ever been in, and he feared that the craft would keep tipping over, forcing an immediate abort.
*Falcon* landed at 104:42:29.3 (22:16:29 GMT on July 30), with approximately 103 seconds of fuel remaining, about 1800 ft from the planned landing site. After Irwin\'s exclamation, Scott reported, \"Okay, Houston. The *Falcon* is on the Plain at Hadley.\" Once within the planned landing zone, the increased mobility provided by the Lunar Roving Vehicle made unnecessary any further maneuvering.
| 937 |
Apollo 15
| 7 |
1,969 |
# Apollo 15
## Mission highlights {#mission_highlights}
### Lunar surface {#lunar_surface}
#### Stand-up EVA and first EVA {#stand_up_eva_and_first_eva}
With *Falcon* due to remain on the lunar surface for almost three days, Scott deemed it important to maintain the circadian rhythm they were used to, and as they had landed in the late afternoon, Houston time, the two astronauts were to sleep before going onto the surface. But the time schedule allowed Scott to open the lander\'s top hatch (usually used for docking) and spend a half hour looking at their surroundings, describing them, and taking photographs. Lee Silver had taught him the importance of going to a high place to survey a new field site, and the top hatch served that purpose. Deke Slayton and other managers were initially opposed due to the oxygen that would be lost, but Scott got his way. During the only stand-up extravehicular activity (EVA) ever performed through the LM\'s top hatch on the lunar surface, Scott was able to make plans for the following day\'s EVA. He offered Irwin a chance to look out as well, but this would have required rearranging the umbilicals connecting Irwin to *Falcon*{{\'s}} life support system, and he declined. After repressurizing the spacecraft, Scott and Irwin removed their space suits for sleep, becoming the first astronauts to doff their suits while on the Moon.
Throughout the sleep period Mission Control in Houston monitored a slow but steady oxygen loss. Scott and Irwin eventually were awakened an hour early, and the source of the problem was found to be an open valve on the urine transfer device. In post-mission debriefing, Scott recommended that future crews be woken at once under similar circumstances. After the problem was solved, the crew began preparation for the first Moon walk.
After donning their suits and depressurizing the cabin, Scott and Irwin began their first full EVA, becoming the seventh and eighth humans, respectively, to walk on the Moon. They began deploying the lunar rover, stored folded up in a compartment of *Falcon*{{\'s}} descent stage, but this proved troublesome due to the slant of the lander. The experts in Houston suggested lifting the front end of the rover as the astronauts pulled it out, and this worked. Scott began a system checkout. One of the batteries gave a zero voltage reading, but this was only an instrumentation problem. A greater concern was that the front wheel steering would not work. However, the rear wheel steering was sufficient to maneuver the vehicle. Completing his checkout, Scott said \"Okay. Out of detent; we\'re moving\", maneuvering the rover away from *Falcon* in mid-sentence. These were the first words uttered by a human while driving a vehicle on the Moon. The rover carried a television camera, controlled remotely from Houston by NASA\'s Ed Fendell. The resolution was not high compared to the still photographs that would be taken, but the camera allowed the geologists on Earth to indirectly participate in Scott and Irwin\'s activities.
The rille was not visible from the landing site, but as Scott and Irwin drove over the rolling terrain, it came into view. They were able to see Elbow crater, and they began to drive in that direction. Reaching Elbow, a known location, allowed Mission Control to backtrack and get closer to pinpointing the location of the lander. The astronauts took samples there, and then drove to another crater on the flank of Mons Hadley Delta, where they took more. After concluding this stop, they returned to the lander to drop off their samples and prepare to set up the Apollo Lunar Surface Experiments Package (ALSEP), the scientific instruments that would remain when they left. Scott had difficulty drilling the holes required for the heat flow experiment, and the work was not completed when they had to return to the lander. The first EVA lasted 6 hours and 32 minutes.
#### Second and third EVAs {#second_and_third_evas}
The rover\'s front steering, inoperative during the first EVA, worked during the second and third ones. The target of the second EVA, on August 1, was the slope of Mons Hadley Delta, where the pair sampled boulders and craters along the Apennine Front. They spent an hour at Spur crater, during which the astronauts collected a sample dubbed the Genesis Rock. This rock, an anorthosite, is believed to be part of the early lunar crust---the hope of finding such a specimen had been one reason the Hadley area had been chosen. Once back at the landing site, Scott continued to try to drill holes for experiments at the ALSEP site, with which he had struggled the day before. After conducting soil-mechanics experiments and raising the U.S. flag, Scott and Irwin returned to the LM. EVA 2 lasted 7 hours and 12 minutes.
Although Scott had eventually been successful at drilling the holes, he and Irwin had been unable to retrieve a core sample, and this was an early order of business during EVA 3, their third and final moonwalk. Time that could have been devoted to geology ticked away as Scott and Irwin attempted to pull it out. Once it had been retrieved, more time passed as they attempted to break the core into pieces for transport to Earth. Hampered by an incorrectly mounted vise on the rover, they eventually gave up on this---the core would be transported home with one segment longer than planned. Scott wondered if the core was worth the amount of time and effort invested, and the CAPCOM, Joe Allen, assured him it was. The core proved one of the most important items brought back from the Moon, revealing much about its history, but the expended time meant the planned visit to a group of hills known as the North Complex had to be scrubbed. Instead, the crew again ventured to the edge of Hadley Rille, this time to the northwest of the immediate landing site.
Once the astronauts were beside the LM, Scott used a kit provided by the Postal Service to cancel a first day cover of two stamps being issued on August 2, the current date. Scott then performed an experiment in view of the television camera, using a falcon feather and hammer to demonstrate Galileo\'s theory that all objects in a given gravity field fall at the same rate, regardless of mass, in the absence of aerodynamic drag. He dropped the hammer and feather at the same time; because of the negligible lunar atmosphere, there was no drag on the feather, which hit the ground at the same time as the hammer. This was Joe Allen\'s idea (he also served as CAPCOM during it) and was part of an effort to find a memorable popular science experiment to do on the Moon along the lines of Shepard\'s hitting of golf balls. The feather was most likely from a female gyrfalcon (a type of falcon), a mascot at the United States Air Force Academy.
Scott then drove the rover to a position away from the LM, where the television camera could be used to observe the lunar liftoff. Near the rover, he left a small aluminum statuette called *Fallen Astronaut*, along with a plaque bearing the names of 14 known American astronauts and Soviet cosmonauts who had died in the furtherance of space exploration. The memorial was left while the television camera was turned away; he told Mission Control he was doing some cleanup activities around the rover. Scott disclosed the memorial in a post-flight news conference. He also placed a Bible on the control panel of the rover before leaving it for the last time to enter the LM.
The EVA lasted 4 hours, 49 minutes and 50 seconds. In total, the two astronauts spent 18`{{frac|1|2}}`{=mediawiki} hours outside the LM and collected approximately 77 kg of lunar samples.
| 1,297 |
Apollo 15
| 8 |
1,969 |
# Apollo 15
## Mission highlights {#mission_highlights}
### Command module activities {#command_module_activities}
After the departure of *Falcon*, Worden in *Endeavour* executed a burn to take the CSM to a higher orbit. While *Falcon* was on the Moon, the mission effectively split, Worden and the CSM being assigned their own CAPCOM and flight support team.
thumb\|upright=1.3\|left\|alt=A spacecraft seen with the Moon in background\|*Endeavour*, with the SIM bay exposed, as seen from the Lunar Module *Falcon* Worden got busy with the tasks that were to occupy him for much of the time he spent in space alone: photography and operating the instruments in the SIM bay. The door to the SIM bay had been explosively jettisoned during the translunar coast. Filling previously unused space in the service module, the SIM bay contained a gamma-ray spectrometer, mounted on the end of a boom, an X-ray spectrometer and a laser altimeter, which failed part way through the mission. Two cameras, a stellar camera and a metric camera, together comprised the mapping camera, which was complemented by a panoramic camera, derived from spy technology. The altimeter and cameras permitted the exact time and location from which pictures were taken to be determined. Also present were an alpha particle spectrometer, which could be used to detect evidence of lunar volcanism, and a mass spectrometer, also on a boom in the hope it would be unaffected by contamination from the ship. The boom would prove troublesome, as Worden would not always be able to get it to retract.
*Endeavour* was slated to pass over the landing site at the moment of planned landing, but Worden could not see *Falcon* and did not spot it until a subsequent orbit. He also exercised to avoid muscle atrophy, and Houston kept him up to date on Scott and Irwin\'s activities on the lunar surface. The panoramic camera did not operate perfectly, but provided enough images that no special adjustment was made. Worden took many photographs through the command module\'s windows, often with shots taken at regular intervals. His task was complicated by the lack of a working mission timer in the Lower Equipment Bay of the command module, as its circuit breaker had popped en route to the Moon. Worden\'s observations and photographs would inform the decision to send Apollo 17 to Taurus-Littrow to search for evidence of volcanic activity. There was a communications blackout when the CSM passed over the far side of the Moon from Earth; Worden greeted each resumption of contact with the words, \"Hello, Earth. Greetings from *Endeavour*\", expressed in different languages. Worden and El-Baz had come up with the idea, and the geology instructor had aided the astronaut in accumulating translations.
Results from the SIM bay experiments would include the conclusion, from data gathered by the X-ray spectrometer, that there was greater fluorescent X-ray flux than anticipated, and that the lunar highlands were richer in aluminum than were the mares. *Endeavour* was in a more inclined orbit than previous crewed missions, and Worden saw features that were not known previously, supplementing photographs with thorough descriptions.
By the time Scott and Irwin were ready to take off from the lunar surface and return to *Endeavour*, the CSM\'s orbit had drifted due to the rotation of the Moon, and a plane change burn was required to ensure that the CSM\'s orbit would be in the same plane as that of the LM once it took off from the Moon. Worden accomplished the 18-second burn with the SPS.
| 580 |
Apollo 15
| 9 |
1,969 |
# Apollo 15
## Mission highlights {#mission_highlights}
### Return to Earth {#return_to_earth}
thumb \|alt=Video showing the lunar lander taking off\|The liftoff from the Moon as seen by the TV camera on the lunar rover *Main article: Return of Apollo 15 to Earth*
*Falcon* lifted off the Moon at 17:11:22 GMT on August 2 after 66 hours and 55 minutes on the lunar surface. Docking with the CSM took place just under two hours later. After the astronauts transferred samples and other items from the LM to the CSM, the LM was sealed off, jettisoned, and intentionally crashed into the lunar surface, an impact registered by the seismometers left by Apollo 12, 14 and 15. The jettison proved difficult because of problems getting airtight seals, requiring a delay in discarding the LM. After the jettison, Slayton came on the loop to recommend the astronauts take sleeping pills, or at least that Scott and Irwin do so. Scott as mission commander refused to allow it, feeling there was no need. During the EVAs, the doctors had noticed irregularities in both Scott\'s and Irwin\'s heartbeats, but the crew were not informed during the flight. Irwin had heart problems after retiring as an astronaut and died in 1991 of a heart attack; Scott felt that he as commander should have been informed of the biomedical readings. NASA doctors at the time theorized the heart readings were due to potassium deficiency, due to their hard work on the surface and inadequate resupply through liquids.
The crew spent the next two days working on orbital science experiments, including more observations of the Moon from orbit and releasing the subsatellite. *Endeavour* departed lunar orbit with another burn of the SPS engine of 2 minutes 21 seconds at 21:22:45 GMT on August 4. The next day, during the return to Earth, Worden performed a 39-minute EVA to retrieve film cassettes from the service module\'s scientific instrument module (SIM) bay, with assistance from Irwin who remained at the command module\'s hatch. At approximately 171,000 nautical miles (197,000 mi; 317,000 km) from Earth, it was the first \"deep space\" EVA in history, performed at great distance from any planetary body. As of `{{year}}`{=mediawiki}, it remains one of only three such EVAs, all performed during Apollo\'s J missions under similar circumstances. Later that day, the crew set a record for the longest Apollo flight to that point.
On approach to Earth on August 7, the service module was jettisoned, and the command module reentered the Earth\'s atmosphere. Although one of the three parachutes on the CM failed after deploying, likely due to damage as the spacecraft vented fuel, only two were required for a safe landing (one extra for redundancy). Upon landing in the North Pacific Ocean, the CM and crew were recovered and taken aboard the recovery ship, `{{USS|Okinawa|LPH-3|6}}`{=mediawiki}, after a mission lasting 12 days, 7 hours, 11 minutes and 53 seconds.
| 482 |
Apollo 15
| 10 |
1,969 |
# Apollo 15
## Assessment
The mission objectives for Apollo 15 were to \"perform selenological inspection, survey, and sampling of materials and surface features in a pre-selected area of the Hadley--Apennine region. Emplace and activate surface experiments. Evaluate the capability of the Apollo equipment to provide extended lunar surface stay time, increased extravehicular operations, and surface mobility. \[and\] Conduct inflight experiments and photographic tasks from lunar orbit.\" It achieved all those objectives. The mission also completed a long list of other tasks, including experiments. One of the photographic objectives, to obtain images of the gegenschein from lunar orbit, was not completed, as the camera was not pointed at the proper spot in the sky. According to the conclusions in the *Apollo 15 Mission Report*, the journey \"was the fourth lunar landing and resulted in the collection of a wealth of scientific information. The Apollo system, in addition to providing a means of transportation, excelled as an operational scientific facility.\"
Apollo 15 saw an increase in public interest in the Apollo program, in part due to fascination with the LRV, as well as the attractiveness of the Hadley Rille site and the increased television coverage. According to David Woods in the *Apollo Lunar Flight Journal*, `{{blockquote|
Though subsequent missions travelled further on the Moon, brought back more samples and put the lessons of Apollo 15 into practice, this feat of unalloyed exploration still stands out as a great moment of human achievement. It is remembered still for its combination of competent enthusiasm, magnificent machinery, finely honed science and the grandeur of a very special site in the cosmos beside a meandering rille and graceful, massive mountains – Hadley Base.<ref group=ALFJ name=summary />
}}`{=mediawiki}
| 282 |
Apollo 15
| 11 |
1,969 |
# Apollo 15
## Controversies
Further information: Apollo 15 postal covers incident
Despite the successful mission, the careers of the crew were tarnished by a deal they had made before the flight to carry postal covers to the Moon in exchange for about \$7,000 each, which they planned to set aside for their children. Walter Eiermann, who had many professional and social contacts with NASA employees and the astronaut corps, served as intermediary between the astronauts and a West German stamp dealer, Hermann Sieger, and Scott carried about 400 covers onto the spacecraft; they were subsequently transferred into *Falcon* and remained inside the lander during the astronauts\' activities on the surface of the Moon. After the return to Earth, 100 of the covers were given to Eiermann, who passed them on to Sieger, receiving a commission. No permission had been received from Slayton to carry the covers, as required.
The 100 covers were put on sale to Sieger\'s customers in late 1971 at a price of about \$1,500 each. After receiving the agreed payments, the astronauts returned them, and accepted no compensation. In April 1972, Slayton learned that unauthorized covers had been carried, and removed the three as the backup crew for Apollo 17. The matter became public in June 1972 and the three astronauts were reprimanded for poor judgment; none ever flew in space again. During the investigation, the astronauts had surrendered those covers still in their possession; after Worden filed suit, they were returned in 1983, something *Slate* magazine deemed an exoneration.
Another controversy arose later, this time surrounding the *Fallen Astronaut* statuette that Scott had left on the Moon. Before the mission, Scott had made a verbal agreement with Belgian artist Paul Van Hoeydonck to sculpt the statuette. Scott\'s intent, in keeping with NASA\'s strict policy against commercial exploitation of the US government\'s space program, was for a simple memorial with a minimum of publicity, keeping the artist anonymous, no commercial replicas being made except for a single copy for public exhibit at the National Air and Space Museum commissioned after the sculpture\'s public disclosure during the post-flight press conference. Van Hoeydonck claims to have had a different understanding of the agreement, by which he would have received recognition as the creator of a tribute to human space exploration, with rights to sell replicas to the public. Under pressure from NASA, Van Hoeydonck canceled a plan to publicly sell 950 signed copies.
In 2021, Scott published a document entitled \"Memorandum for the Record\", in which he stated that the figurine left on the Moon was designed and fabricated by NASA personnel. While testifying before a Senate committee in 1972, he had stated that the figurine had been made and provided by Van Hoeydonck at Scott\'s request.
During those congressional hearings into the postal covers and Fallen Astronaut matters, two Bulova timepieces taken on the mission by Scott were also matters of controversy. Before the mission, Scott had been introduced to Bulova\'s representative, General James McCormack by Apollo 8 commander Frank Borman. Bulova had been seeking to have its timepieces taken on Apollo missions, but after evaluation, NASA had selected Omega watches instead. Scott brought the Bulova timepieces on the mission, without disclosing them to Slayton. During Scott\'s second EVA, the crystal on his NASA standard issue Omega Speedmaster watch popped off, and, during the third EVA, he used a Bulova watch. The Bulova Chronograph Model #88510/01 that Scott wore on the lunar surface was a prototype, given to him by the Bulova Company, and it is the only privately owned watch to have been worn while walking on the lunar surface. There are images of him wearing this watch, when he saluted the American flag on the Moon, with the Hadley Delta expanse in the background. In 2015, the watch sold for \$1.625 million, which makes it one of the most expensive astronaut-owned artifact ever sold at auction and one of the most expensive watches sold at auction.
## Mission insignia {#mission_insignia}
The Apollo 15 mission patch carries Air Force motifs, a nod to the crew\'s service there, just as the Apollo 12 all-Navy crew\'s patch had featured a sailing ship. The circular patch features stylized red, white and blue birds flying over Hadley Rille. Immediately behind the birds, a line of craters forms the Roman numeral XV. The Roman numerals were hidden in emphasized outlines of some craters after NASA insisted that the mission number be displayed in Arabic numerals. The artwork is circled in red, with a white band giving the mission and crew names and a blue border. Scott contacted fashion designer Emilio Pucci to design the patch, who came up with the basic idea of the three-bird motif on a square patch.
The crew changed the shape to round and the colors from blues and greens to a patriotic red, white and blue. Worden stated that each bird also represented an astronaut, white being his own color (and as Command Module Pilot, uppermost), Scott being the blue bird and Irwin the red. The colors matched Chevrolet Corvettes leased by the astronauts at KSC; a Florida car dealer had, since the time of Project Mercury, been leasing Chevrolets to astronauts for \$1 and later selling them to the public. The astronauts were photographed with the cars and the training LRV for the June 11, 1971, edition of *Life* magazine.
| 895 |
Apollo 15
| 12 |
1,969 |
# Apollo 15
## Visibility from space {#visibility_from_space}
The halo area of the Apollo 15 landing site, created by the LM\'s exhaust plume, was observed by a camera aboard the Japanese lunar orbiter SELENE and confirmed by comparative analysis of photographs in May 2008. This corresponds well to photographs taken from the Apollo 15 command module showing a change in surface reflectivity due to the plume, and was the first visible trace of crewed landings on the Moon seen from space since the close of the Apollo program.
## Gallery
### Still images {#still_images}
<File:Apollo> 15 rollout from VAB.jpg\|alt=A rocket on a launchpad\|The Apollo 15 launch vehicle during rollout <File:Jim> Irwin (left) Al Worden, and Dave Scott pose in front of the VAB during the Saturn V roll-out.jpg\|alt=Three men stand in front of a rocket\|The astronauts pose before the VAB as the Saturn V is rolled out <File:Al> Worden, Dave Scott, Deke Slayton, and Jack Schmitt dig into the pre-launch breakfast.jpg\|alt=Several men at a sit-down breakfast\|Worden, Scott, Slayton and Schmitt eat the pre-launch breakfast <File:Falcon> lunar module on the Moon.jpg\|alt=A lunar landscape with a lander in the background\|*Falcon* on the Moon. Note the slant of the vehicle <File:Apollo> 15 Station 2 Rille, Lunar Rover, Scott.jpg\|alt=Lunar landscape with man leaning over rover\|Scott does geology work near Hadley Rille <File:Apollo> 15 Dave Scott at St. 9a.jpg\|alt=A man in a spacesuit leans over a large rock\|Scott examines a boulder during the third EVA <File:A15.s74> 41836.jpg\|alt=A control room; visible on a large screen are two astronauts walking on the Moon\|Mission Control in Houston during the third Apollo 15 EVA, August 2, 1971. CAPCOM Joe Allen is to left (pointing) with Dick Gordon next to him. <File:S71-41759.jpg%7Calt=Several> rows of consoles. A large screen showed a lunar lander\|Mission Control in Houston as *Falcon* takes off from the Moon <File:Worden> podczas EVA S71-43202.jpg\|alt=A man in a spacesuit floating beside a spacecraft\|Alfred Worden in space suit retrieving film cartridges during the transearth coast <File:S71-42825.jpg%7Calt=Three> men in flight suits disembark a helicopter\|The astronauts disembark their helicopter aboard the *Okinawa* <File:Moon> AS15-M-2778.jpg\|alt=The Moon\|The Moon as seen from the departing Apollo 15 spacecraft <File:Stafford> Air & Space Museum, Weatherford, OK, US (60).jpg\|alt=A plaque to be left on the lander\|Backup of the plaque left on *Falcon*{{\'s}} descent stage <File:Apollo> 15 Command Module at the National Museum of the United States Air Force.jpg\|alt=A spaceship on display\|Command Module *Endeavour* on display at the National Museum of the United States Air Force in Dayton, Ohio <File:Apollo> 15 Space Suit David Scott.jpg\|The spacesuit David Scott wore during the Apollo 15 mission is on display at the National Air and Space Museum, Washington, D.C.
### Multimedia
<File:Apollo> 15 CSM moving away from LM.ogv \|alt=Film of a spacecraft in space\|*Endeavour* filmed from *Falcon* after undocking <File:Apollo> 15 Lunar Roving Vehicle deployment.webm\|alt=The lunar rover is set up\|Deployment of the lunar rover on the Moon <File:Apollo> 15 liftoff from inside LM.ogv\|alt=A spacecraft takes off from the Moon\|Liftoff from the Moon, seen through the LMP\'s window as Scott and Irwin play a prerecorded instrumental version of the song \"The U.S. Air Force\", commonly known as \"Wild Blue Yonder\". <File:Apollo> 15 splashdown
| 520 |
Apollo 15
| 13 |
1,974 |
# April 17
| 3 |
April 17
| 0 |
2,003 |
# Argument from morality
The **argument from morality** is an argument for the existence of God. Arguments from morality tend to be based on moral normativity or moral order. Arguments from moral normativity observe some aspect of morality and argue that God is the best or only explanation for this, concluding that God must exist. Arguments from moral order are based on the asserted need for moral order to exist in the universe. They claim that, for this moral order to exist, God must exist to support it. The argument from morality is noteworthy in that one cannot evaluate the soundness of the argument without attending to almost every important philosophical issue in meta-ethics.
German philosopher Immanuel Kant devised an argument from morality based on practical reason. Kant argued that the goal of humanity is to achieve perfect happiness and virtue (the *summum bonum*) and believed that an afterlife must be assumed to exist in order for this to be possible, and that God must be assumed to exist to provide this. Rather than aiming to prove the existence of God, however, Kant was simply attempting to demonstrate that all moral thought requires the assumption that God exists, and therefore that we are entitled to make such an assumption only as a regulative principle rather than a constitutive principle (meaning that such a principle can guide our actions, but it does not provide knowledge). In his book *Mere Christianity*, C. S. Lewis argued that \"conscience reveals to us a moral law whose source cannot be found in the natural world, thus pointing to a supernatural Lawgiver.\" Lewis argued that accepting the validity of human reason as a given must include accepting the validity of practical reason, which could not be valid without reference to a higher cosmic moral order which could not exist without a God to create and/or establish it. A related argument is from conscience; John Henry Newman argued that the conscience supports the claim that objective moral truths exist because it drives people to act morally even when it is not in their own interest. Newman argued that, because the conscience suggests the existence of objective moral truths, God must exist to give authority to these truths.
Contemporary defenders of the argument from morality are Graham Ward, Alister McGrath and William Lane Craig.
| 386 |
Argument from morality
| 0 |
2,003 |
# Argument from morality
## General form {#general_form}
All variations of the argument from morality begin with an observation about moral thought or experiences and conclude with the existence of God. Some of these arguments propose moral facts which they claim evident through human experience, arguing that God is the best explanation for these. Other versions describe some end which humans should strive to attain that is only possible if God exists.
Many arguments from morality are based on moral normativity, which suggests that objective moral truths exist and require God\'s existence to give them authority. Often, they consider that morality seems to be binding -- obligations are seen to convey more than just a preference, but imply that the obligation will stand, regardless of other factors or interests. For morality to be binding, God must exist. In its most general form, the argument from moral normativity is:
1. A human experience of morality is observed.
2. God is the best or only explanation for this moral experience.
3. Therefore, God exists.`{{Failed verification|date=April 2020}}`{=mediawiki}
Some arguments from moral order suggest that morality is based on rationality and that this can only be the case if there is a moral order in the universe. The arguments propose that only the existence of God as orthodoxly conceived could support the existence of moral order in the universe, so God must exist. Alternative arguments from moral order have proposed that we have an obligation to attain the perfect good of both happiness and moral virtue. They attest that whatever we are obliged to do must be possible, and achieving the perfect good of both happiness and moral virtue is only possible if a natural moral order exists. A natural moral order requires the existence of God as orthodoxly conceived, so God must exist.
| 300 |
Argument from morality
| 1 |
2,003 |
# Argument from morality
## Variations
### Practical reason {#practical_reason}
In his *Critique of Pure Reason*, German philosopher Immanuel Kant stated that no successful argument for God\'s existence arises from reason alone. In his *Critique of Practical Reason* he went on to argue that, despite the failure of these arguments, morality requires that God\'s existence is assumed, owing to practical reason. Rather than proving the existence of God, Kant was attempting to demonstrate that all moral thought requires the assumption that God exists. Kant argued that humans are obliged to bring about the *summum bonum*: the two central aims of moral virtue and happiness, where happiness arises out of virtue. As ought implies can, Kant argued, it must be possible for the *summum bonum* to be achieved. He accepted that it is not within the power of humans to bring the *summum bonum* about, because we cannot ensure that virtue always leads to happiness, so there must be a higher power who has the power to create an afterlife where virtue can be rewarded by happiness.
Philosopher G. H. R. Parkinson notes a common objection to Kant\'s argument: that what ought to be done does not necessarily entail that it is possible. He also argues that alternative conceptions of morality exist which do not rely on the assumptions that Kant makes -- he cites utilitarianism as an example which does not require the *summum bonum*. Nicholas Everitt argues that much moral guidance is unattainable, such as the Biblical command to be Christ-like. He proposes that Kant\'s first two premises only entail that we must try to achieve the perfect good, not that it is actually attainable.
### Argument from objective moral truths {#argument_from_objective_moral_truths}
Both theists and non-theists have accepted that the existence of objective moral truths might entail the existence of God. Atheist philosopher J. L. Mackie accepted that, if objective moral truths existed, they would warrant a supernatural explanation. Scottish philosopher W. R. Sorley presented the following argument:
1. If morality is objective and absolute, God must exist.
2. Morality is objective and absolute.
3. Therefore, God must exist.
Many critics have challenged the second premise of this argument, by offering a biological and sociological account of the development of human morality which suggests that it is neither objective nor absolute. This account, supported by biologist E. O. Wilson and philosopher Michael Ruse, proposes that the human experience of morality is a by-product of natural selection, a theory philosopher Mark D. Linville calls evolutionary naturalism. According to the theory, the human experience of moral obligations was the result of evolutionary pressures, which attached a sense of morality to human psychology because it was useful for moral development; this entails that moral values do not exist independently of the human mind. Morality might be better understood as an evolutionary imperative in order to propagate genes and ultimately reproduce. No human society today advocates immorality, such as theft or murder, because it would undoubtedly lead to the end of that particular society and any chance for future survival of offspring. Scottish empiricist David Hume made a similar argument, that belief in objective moral truths is unwarranted and to discuss them is meaningless.
Because evolutionary naturalism proposes an empirical account of morality, it does not require morality to exist objectively; Linville considers the view that this will lead to moral scepticism or antirealism. C. S. Lewis argued that, if evolutionary naturalism is accepted, human morality cannot be described as absolute and objective because moral statements cannot be right or wrong. Despite this, Lewis argued, those who accept evolutionary naturalism still act as if objective moral truths exist, leading Lewis to reject naturalism as incoherent. As an alternative ethical theory, Lewis offered a form of divine command theory which equated God with goodness and treated goodness as an essential part of reality, thus asserting God\'s existence.
J. C. A. Gaskin challenges the first premise of the argument from moral objectivity, arguing that it must be shown why absolute and objective morality entails that morality is commanded by God, rather than simply a human invention. It could be the consent of humanity that gives it moral force, for example. American philosopher Michael Martin argues that it is not necessarily true that objective moral truths must entail the existence of God, suggesting that there could be alternative explanations: he argues that naturalism may be an acceptable explanation and, even if a supernatural explanation is necessary, it does not have to be God (polytheism is a viable alternative). Martin also argues that a non-objective account of ethics might be acceptable and challenges the view that a subjective account of morality would lead to moral anarchy.
William Lane Craig has argued for this form of the moral argument.
### Argument for conscience {#argument_for_conscience}
Related to the argument from morality is the argument from conscience, associated with eighteenth-century bishop Joseph Butler and nineteenth-century cardinal John Henry Newman. Newman proposed that the conscience, as well as giving moral guidance, provides evidence of objective moral truths which must be supported by the divine. He argued that emotivism is an inadequate explanation of the human experience of morality because people avoid acting immorally, even when it might be in their interests. Newman proposed that, to explain the conscience, God must exist.
British philosopher John Locke argued that moral rules cannot be established from conscience because the differences in people\'s consciences would lead to contradictions. Locke also noted that the conscience is influenced by \"education, company, and customs of the country\", a criticism mounted by J. L. Mackie, who argued that the conscience should be seen as an \"introjection\" of other people into an agent\'s mind. Michael Martin challenges the argument from conscience with a naturalistic account of conscience, arguing that naturalism provides an adequate explanation for the conscience without the need for God\'s existence. He uses the example of the internalization by humans of social pressures, which leads to the fear of going against these norms. Even if a supernatural cause is required, he argues, it could be something other than God; this would mean that the phenomenon of the conscience is no more supportive of monotheism than polytheism.
C. S. Lewis argues for the existence of God in a similar way in his book *Mere Christianity*, but he does not directly refer to it as the argument from morality
| 1,059 |
Argument from morality
| 2 |
2,014 |
# Atomic semantics
**Atomic semantics** is a type of guarantee provided by a data register shared by several processors in a parallel machine or in a network of computers working together. Atomic semantics are very strong. An atomic register provides strong guarantees even when there is concurrency and failures.
A read/write register R stores a value and is accessed by two basic operations: read and write(v). A read returns the value stored in R and write(v) changes the value stored in R to v. A register is called atomic if it satisfies the two following properties:
1\) Each invocation op of a read or write operation:
•Must appear as if it were executed at a single point τ(op) in time.
•τ (op) works as follow: τb(op) ≤ τ (op) ≤ τe(op): where τb(op) and τe(op) indicate the time when the operation op begins and ends.
•If op1 ≠ op2, then τ (op1)≠τ (op2)
2\) Each read operation returns the value written by the last write operation before the read, in the sequence where all operations are ordered by their τ values.
**Atomic/Linearizable register:**
Termination: when a node is correct, sooner or later each read and write operation will complete.
**Safety Property** (Linearization points for read and write and failed operations):
Read operation:It appears as if happened at all nodes at some times between the invocation and response time.
Write operation: Similar to read operation, it appears as if happened at all nodes at some times between the invocation and response time.
Failed operation(The atomic term comes from this notion):It appears as if it is completed at every single node or it never happened at any node.
Example : We know that an atomic register is one that is linearizable to a sequential safe register.
The following picture shows where we should put the linearization point for each operation:
An atomic register could be defined for a variable with a single writer but multi- readers (SWMR), single-writer/single-reader (SWSR), or multi-writer/multi-reader (MWMR). Here is an example of a multi-reader multi-writer atomic register which is accessed by three processes (P1, P2, P3). Note that R. read() → v means that the corresponding read operation returns v, which is the value of the register. Therefore, the following execution of the register R could satisfies the definition of the atomic registers: R.write(1), R.read()→1, R.write(3), R.write(2), R.read()→2, R.read()→2
| 392 |
Atomic semantics
| 0 |
2,015 |
# Antarctic Circumpolar Current
**Antarctic Circumpolar Current** (**ACC**) is an ocean current that flows clockwise (as seen from the South Pole) from west to east around Antarctica. An alternative name for the ACC is the **West Wind Drift**. The ACC is the dominant circulation feature of the Southern Ocean and has a mean transport estimated at 137 ± 7 Sverdrups (Sv, million m^3^/s), or possibly even higher, making it the largest ocean current. The current is circumpolar due to the lack of any landmass connecting with Antarctica and this keeps warm ocean waters away from Antarctica, enabling that continent to maintain its huge ice sheet.
Associated with the Circumpolar Current is the Antarctic Convergence, where the cold Antarctic waters meet the warmer waters of the subantarctic, creating a zone of upwelling nutrients. These nurture high levels of phytoplankton with associated copepods and krill, and resultant food chains supporting fish, whales, seals, penguins, albatrosses, and a wealth of other species.
The ACC has been known to sailors for centuries; it greatly speeds up any travel from west to east, but makes sailing extremely difficult from east to west, although this is mostly due to the prevailing westerly winds. Jack London\'s story \"Make Westing\" and the circumstances preceding the mutiny on the *Bounty* poignantly illustrate the difficulty it caused for mariners seeking to round Cape Horn westbound on the clipper ship route from New York to California. The eastbound clipper route, which is the fastest sailing route around the world, follows the ACC around three continental capes -- Cape Agulhas (Africa), South East Cape (Australia), and Cape Horn (South America).
The current creates the Ross and Weddell Gyres.
| 276 |
Antarctic Circumpolar Current
| 0 |
2,015 |
# Antarctic Circumpolar Current
## Structure
The ACC connects the Atlantic, Pacific, and Indian Oceans, and serves as a principal pathway of exchange among them. The current is strongly constrained by landform and bathymetric features. To trace it starting arbitrarily at South America, it flows through the Drake Passage between South America and the Antarctic Peninsula and then is split by the Scotia Arc to the east, with a shallow warm branch flowing to the north in the Falkland Current and a deeper branch passing through the Arc more to the east before also turning to the north. Passing through the Indian Ocean, the current first retroflects the Agulhas Current to form the Agulhas Return Current before it is split by the Kerguelen Plateau, and then moving northward again. Deflection is also seen as it passes over the mid-ocean ridge in the Southeast Pacific.
### Fronts
The current is accompanied by three fronts: the Subantarctic front (SAF), the Polar front (PF), and the Southern ACC front (SACC). Furthermore, the waters of the Southern Ocean are separated from the warmer and saltier subtropical waters by the subtropical front (STF).
The northern boundary of the ACC is defined by the northern edge of the SAF, this being the most northerly water to pass through Drake Passage and therefore be circumpolar. Much of the ACC transport is carried in this front, which is defined as the latitude at which a subsurface salinity minimum or a thick layer of unstratified Subantarctic mode water first appears, allowed by temperature dominating density stratification. Still further south lies the PF, which is marked by a transition to very cold, relatively fresh, Antarctic Surface Water at the surface. Here a temperature minimum is allowed by salinity dominating density stratification, due to the lower temperatures. Farther south still is the SACC, which is determined as the southernmost extent of Circumpolar deep water (temperature of about 2 °C at 400 m). This water mass flows along the shelfbreak of the western Antarctic Peninsula and thus marks the most southerly water flowing through Drake Passage and therefore circumpolar. The bulk of the transport is carried in the middle two fronts.
The total transport of the ACC at Drake Passage is estimated to be around 135 Sv, or about 135 times the transport of all the world\'s rivers combined. There is a relatively small addition of flow in the Indian Ocean, with the transport south of Tasmania reaching around 147 Sv, at which point the current is probably the largest on the planet.
| 421 |
Antarctic Circumpolar Current
| 1 |
2,015 |
# Antarctic Circumpolar Current
## Dynamics
The circumpolar current is driven by the strong westerly winds in the latitudes of the Southern Ocean.
In latitudes where there are continents, winds blowing on light surface water can simply pile up light water against these continents. But in the Southern Ocean, the momentum imparted to the surface waters cannot be offset in this way. There are different theories on how the Circumpolar Current balances the momentum imparted by the winds. The increasing eastward momentum imparted by the winds causes water parcels to drift outward from the axis of the Earth\'s rotation (in other words, northward) as a result of the Coriolis force. This northward Ekman transport is balanced by a southward, pressure-driven flow below the depths of the major ridge systems. Some theories connect these flows directly, implying that there is significant upwelling of dense deep waters within the Southern Ocean, transformation of these waters into light surface waters, and a transformation of waters in the opposite direction to the north. Such theories link the magnitude of the Circumpolar Current with the global thermohaline circulation, particularly the properties of the North Atlantic.
Alternatively, ocean eddies, the oceanic equivalent of atmospheric storms, or the large-scale meanders of the Circumpolar Current may directly transport momentum downward in the water column. This is because such flows can produce a net southward flow in the troughs and a net northward flow over the ridges without requiring any transformation of density. In practice both the thermohaline and the eddy/meander mechanisms are likely to be important.
The current flows at a rate of about 4 km/h over the Macquarie Ridge south of New Zealand. The ACC varies with time. Evidence of this is the Antarctic Circumpolar Wave, a periodic oscillation that affects the climate of much of the southern hemisphere. There is also the Antarctic oscillation, which involves changes in the location and strength of Antarctic winds. Trends in the Antarctic Oscillation have been hypothesized to account for an increase in the transport of the Circumpolar Current over the past two decades.
## Formation
Published estimates of the onset of the Antarctic Circumpolar Current vary, but it is commonly considered to have started at the Eocene/Oligocene boundary. The isolation of Antarctica and formation of the ACC occurred with the openings of the Tasmanian Passage and the Drake Passage, following the fragmentation of the Antarctic land bridge. The Tasmanian Seaway separates East Antarctica and Australia, and is reported to have opened to water circulation 33.5 million years ago (Ma). The timing of the opening of the Drake Passage, between South America and the Antarctic Peninsula, is more disputed. Tectonic and sediment evidence show that it could have been open as early as pre-34 Ma; estimates of the opening of the Drake passage are between 20 and 40 Ma. The isolation of Antarctica by the current is credited by many researchers with causing the glaciation of Antarctica and global cooling in the Eocene epoch. Oceanic models have shown that the opening of these two passages limited polar heat convergence and caused a cooling of sea surface temperatures by several degrees; other models have shown that CO~2~ levels also played a significant role in the glaciation of Antarctica.
| 537 |
Antarctic Circumpolar Current
| 2 |
2,015 |
# Antarctic Circumpolar Current
## Phytoplankton
Antarctic sea ice cycles seasonally, in February--March the amount of sea ice is lowest, and in August--September the sea ice is at its greatest extent. Ice levels have been monitored by satellite since 1973. Upwelling of deep water under the sea ice brings substantial amounts of nutrients. As the ice melts, the melt water provides stability and the critical depth is well below the mixing depth, which allows for a positive net primary production. As the sea ice recedes epontic algae dominate the first phase of the bloom, and a strong bloom dominate by diatoms follows the ice melt south.
Another phytoplankton bloom occurs more to the north near the Antarctic Convergence, here nutrients are present from thermohaline circulation. Phytoplankton blooms are dominated by diatoms and grazed by copepods in the open ocean, and by krill closer to the continent. Diatom production continues through the summer, and populations of krill are sustained, bringing large numbers of cetaceans, cephalopods, seals, birds, and fish to the area.
Phytoplankton blooms are believed to be limited by irradiance in the austral (southern hemisphere) spring, and by biologically available iron in the summer. Much of the biology in the area occurs along the major fronts of the current, the Subtropical, Subantarctic, and the Antarctic Polar fronts, these are areas associated with well defined temperature changes. Size and distribution of phytoplankton are also related to fronts. Microphytoplankton (\>20 μm) are found at fronts and at sea ice boundaries, while nanophytoplankton (\<20 μm) are found between fronts.
Studies of phytoplankton stocks in the southern sea have shown that the Antarctic Circumpolar Current is dominated by diatoms, while the Weddell Sea has abundant coccolithophorids and silicoflagellates. Surveys of the SW Indian Ocean have shown phytoplankton group variation based on their location relative to the Polar Front, with diatoms dominating South of the front, and dinoflagellates and flagellates in higher populations North of the front.
Some research has been conducted on Antarctic phytoplankton as a carbon sink. Areas of open water left from ice melt are good areas for phytoplankton blooms. The phytoplankton takes carbon from the atmosphere during photosynthesis. As the blooms die and sink, the carbon can be stored in sediments for thousands of years. This natural carbon sink is estimated to remove 3.5 million tonnes from the ocean each year. 3.5 million tonnes of carbon taken from the ocean and atmosphere is equivalent to 12.8 million tonnes of carbon dioxide.
| 410 |
Antarctic Circumpolar Current
| 3 |
2,015 |
# Antarctic Circumpolar Current
## Studies
An expedition in May 2008 by 19 scientists studied the geology and biology of eight Macquarie Ridge sea mounts, as well as the Antarctic Circumpolar Current to investigate the effects of climate change of the Southern Ocean. The circumpolar current merges the waters of the Atlantic, Indian, and Pacific Oceans and carries up to 150 times the volume of water flowing in all of the world\'s rivers. The study found that any damage on the cold-water corals nourished by the current will have a long-lasting effect. After studying the circumpolar current it is clear that it strongly influences regional and global climate as well as underwater biodiversity. The subject has been characterized recently as \"the spectral peak of the global extra-tropical circulation at ≈ 10\^4 kilometers\".
The current helps preserve wooden shipwrecks by preventing wood-boring \"ship worms\" from reaching targets such as Ernest Shackleton\'s ship, the *Endurance*.
The \"State of the Cryosphere\" report found, that the Antarctic Circumpolar Current became weaker. By 2050 it expected to lose 20% of its strength with \"widespread impacts on ocean circulation and climate.\" The Weddell Sea Bottom Water has lost 30% of its volume in the latest 32 years, and the Antarctic Bottom Water is expected to shrink. This will impact ocean circulation, nutrients, heat content and carbon sequestration. UNESCO mentions that the report in the first time \"notes a growing scientific consensus that melting Greenland and Antarctic ice sheets, among other factors, may be slowing important ocean currents at both poles, with potentially dire consequences for a much colder northern Europe and greater sea-level rise along the U.S. East Coast.\" The findings were bolstered by a 2025 study published in Environmental Research Letters
| 286 |
Antarctic Circumpolar Current
| 4 |
2,037 |
# Delian League
Delyan}}
The **Delian League** was a confederacy of Greek city-states, numbering between 150 and 330, founded in 478 BC under the leadership (hegemony) of Athens, whose purpose was to continue fighting the Persian Empire after the Greek victory in the Battle of Plataea at the end of the Second Persian invasion of Greece. The League functioned as a dual --offensive and defensive-- alliance (*symmachia*) of autonomous states, similar to its rival association, the Peloponnesian League. The League\'s modern name derives from its official meeting place, the island of Delos, where congresses were held within the sanctuary of the Temple of Apollo; contemporary authors referred to the organization simply as \"the Athenians and their Allies\".
While Sparta excelled as Greece\'s greatest power on land, Athens turned to the seas becoming the dominant naval power of the Greek world. Following Sparta\'s withdrawal from the conflict with Persia, Athens took the lead of the Hellenic alliance accompanied by several states around the Aegean and the Anatolian coast. The Delian League was formed as an anti-Persian defensive association of equal city-states seeking protection under Athens, as the latter wished to extend its support towards the Ionian Greek colonies of Anatolia. By the mid-fifth century BC, the alliance had developed into a naval imperial power, called the **Athenian Empire**, where Athens established complete dominion and the allies became increasingly less autonomous. The alliance held an assembly of representatives in order to shape its policy, while the members swore an oath of loyalty to the coalition. The Delian League successfully accomplished its principal strategic goal by decisively expelling the remaining Persian forces from the Aegean. As a result, Persia would cease to pose a major threat to Greece for the following fifty years.
From its inception, Athens became the League\'s biggest source of military power, while more and more allies preferred to pay the dues in cash. Athens began to use the League\'s funds for its own purposes, like the reinforcement of its naval supremacy, which led to conflicts between the city and its less powerful allies, at times culminating in rebellions, like that of Thasos in 465 BC. The League\'s treasury initially stood in Delos until, in a symbolic gesture, Pericles moved it to Athens in 454 BC. By 431 BC, the threat that the League presented to Spartan hegemony combined with Athens\'s heavy-handed control of the Delian League prompted the outbreak of the Peloponnesian War; the League was dissolved upon the war\'s conclusion in 404 BC under the direction of Lysander, the Spartan commander. Witnessing Sparta\'s growing hegemony in the first half of the 4th century BC, Athens went on to partly revive the alliance, this time called the Second Athenian League, reestablishing its naval dominance in the eastern Mediterranean.
| 459 |
Delian League
| 0 |
2,037 |
# Delian League
## Background
thumb\|upright=1.5\|Athenian Empire in 445 BC, according to the Tribute Lists. The islands of Lesbos, Chios and Samos (shaded on the map) did not pay tribute. The Greco-Persian Wars had their roots in the conquest of the Greek cities of Asia Minor, and particularly Ionia, by the Achaemenid Persian Empire of Cyrus the Great shortly after 550 BC. The Persians found the Ionians difficult to rule, eventually settling for sponsoring a tyrant in each Ionian city. While Greek states had in the past often been ruled by tyrants, this form of government was on the decline. By 500 BC, Ionia appears to have been ripe for rebellion against these Persian clients. The simmering tension finally broke into open revolt due to the actions of the tyrant of Miletus, Aristagoras. Attempting to save himself after a disastrous Persian-sponsored expedition in 499 BC, Aristagoras chose to declare Miletus a democracy. This triggered similar revolutions across Ionia, extending to Doris and Aeolis, beginning the Ionian Revolt.
The Greek states of Athens and Eretria allowed themselves to be drawn into this conflict by Aristagoras, and during their only campaigning season (498 BC) they contributed to the capture and burning of the Persian regional capital of Sardis. After this, the Ionian revolt carried on (without further outside aid) for a further five years, until it was finally completely crushed by the Persians. However, in a decision of great historic significance, the Persian king Darius the Great decided that, despite having subdued the revolt, there remained the unfinished business of exacting punishment on Athens and Eretria for supporting the revolt. The Ionian revolt had severely threatened the stability of Darius\'s empire, and the states of mainland Greece would continue to threaten that stability unless dealt with. Darius thus began to contemplate the complete conquest of Greece, beginning with the destruction of Athens and Eretria.
In the next two decades, there would be two Persian invasions of Greece, occasioning, thanks to Greek historians, some of the most famous battles in history. During the first invasion, Thrace, Macedon and the Aegean Islands were added to the Persian Empire, and Eretria was duly destroyed. However, the invasion ended in 490 BC with the decisive Athenian victory at the Battle of Marathon. After this invasion, Darius died, and responsibility for the war passed to his son Xerxes I.
Xerxes then personally led a second Persian invasion of Greece in 480 BC, taking an enormous (although oft-exaggerated) army and navy to Greece. Those Greeks who chose to resist (the \'Allies\') were defeated in the twin simultaneous battles of Thermopylae on land and Artemisium at sea. All of Greece except the Peloponnesus thus having fallen into Persian hands, the Persians then seeking to destroy the Allied navy once and for all, suffered a decisive defeat at the Battle of Salamis. The following year, 479 BC, the Allies assembled the largest Greek army yet seen and defeated the Persian invasion force at the Battle of Plataea, ending the invasion and the threat to Greece.
The Allied fleet defeated the remnants of the Persian fleet in the Battle of Mycale near the island of Samos---on the same day as Plataea, according to tradition. This action marks the end of the Persian invasion, and the beginning of the next phase in the Greco-Persian wars, the Greek counterattack. After Mycale, the Greek cities of Asia Minor again revolted, with the Persians now powerless to stop them. The Allied fleet then sailed to the Thracian Chersonese, still held by the Persians, and besieged and captured the town of Sestos. The following year, 478 BC, the Allies sent a force to capture the city of Byzantion (modern day Istanbul). The siege was successful, but the behaviour of the Spartan general Pausanias alienated many of the Allies, and resulted in Pausanias\'s recall.
| 637 |
Delian League
| 1 |
2,037 |
# Delian League
## Formation
After Byzantion, Sparta was eager to end its involvement in the war. The Spartans greatly feared the rise of the Athenians as a challenge to their power. Additionally, the Spartans were of the view that, with the liberation of mainland Greece, and the Greek cities of Asia Minor, the war\'s purpose had already been achieved. There was also perhaps a feeling that establishing long-term security for the Asian Greeks would prove impossible. In the aftermath of Mycale, the Spartan king Leotychidas had proposed transplanting all the Greeks from Asia Minor to Europe as the only method of permanently freeing them from Persian dominion.
Xanthippus, the Athenian commander at Mycale, had furiously rejected this; the Ionian cities had been Athenian colonies, and the Athenians, if no one else, would protect the Ionians. This marked the point at which the leadership of the Greek alliance effectively passed to the Athenians. With the Spartan withdrawal after Byzantion, the leadership of the Athenians became explicit.
The loose alliance of city states which had fought against Xerxes\'s invasion had been dominated by Sparta and the Peloponnesian league. With the withdrawal of these states, a congress was called on the holy island of Delos to institute a new alliance to continue the fight against the Persians; hence the modern designation \"Delian League\". According to Thucydides, the official aim of the League was to \"avenge the wrongs they suffered by ravaging the territory of the king.\"
In reality, this goal was divided into three main efforts---to prepare for future invasion, to seek revenge against Persia, and to organize a means of dividing spoils of war. The members were given a choice of either offering armed forces or paying a tax to the joint treasury; most states chose the tax. League members swore to have the same friends and enemies, and dropped ingots of iron into the sea to symbolize the permanence of their alliance. The Athenian politician Aristides would spend the rest of his life occupied in the affairs of the alliance, dying (according to Plutarch) a few years later in Pontus, whilst determining what the tax of new members was to be.
| 361 |
Delian League
| 2 |
2,037 |
# Delian League
## Members
The Delian League, also known as the Athenian Empire, was a collection of Greek city-states largely based around the Aegean Sea which operated under the hegemony of Athens. This alliance initially served the purpose of coordinating a united Greek front against a perceived looming Persian threat against the Ionian city-states which bordered it. The members of the Delian League were made to swear an oath of loyalty to the league and contributed mostly monetarily but in some instances donated ships or other forces. It was also the case that many democratic members of the League owed their freedom from oligarchic or tyrannical rule to Athens. Because of this, Athens gained an overwhelming advantage in the voting system conducted by relying on the support of democratic city-states Athens had helped into being. By 454 Athens moved the treasury of the Delian League from the Island of Delos to the Parthenon in Athens. Benefitting greatly from the influx of cash coming out of the 150-330 members, Athens used the money to reinforce its own naval supremacy and used the remaining funds to embellish the city with art and architecture. In order to maintain the new synoecism, Athens began using its greatly expanded military to enforce membership in the League. City-states who wished to leave the alliance were punished by Athens with force such as Mytilene and Melos. No longer considered her allies, Athens eventually began to refer to the members of the Delian League as \"all the cities Athens rules.\" Athens also extended its authority over members of the League through judicial decisions. Synoecism under the Athenian Empire was enforced by resolving matters of and between states in Athens by courts composed of Athenian citizens and enforcing those decisions through the Athenian military.
## Composition and expansion {#composition_and_expansion}
In the first ten years of the league\'s existence, Cimon/Kimon forced Karystos in Euboea to join the league, conquered the island of Skyros and sent Athenian colonists there.
Over time, especially with the suppression of rebellions, Athens exercised hegemony over the rest of the league. Thucydides describes how Athens\'s control over the League grew:
> Of all the causes of defection, that connected with arrears of tribute and vessels, and with failure of service, was the chief; for the Athenians were very severe and exacting, and made themselves offensive by applying the screw of necessity to men who were not used to and in fact not disposed for any continuous labor. In some other respects the Athenians were not the old popular rulers they had been at first; and if they had more than their fair share of service, it was correspondingly easy for them to reduce any that tried to leave the confederacy. The Athenians also arranged for the other members of the league to pay its share of the expense in money instead of in ships and men, and for this the subject city-states had themselves to blame, their wish to get out of giving service making most leave their homes. Thus while Athens was increasing her navy with the funds they contributed, a revolt always found itself without enough resources or experienced leaders for war.
## Rebellion
### Naxos
The first member of the league to attempt to secede was the island of Naxos in c. 471 BC. After being defeated, Naxos is believed (based on similar, later revolts) to have been forced to tear down its walls along with losing its fleet and vote in the League.
### Thasos
In 465 BC, Athens founded the colony of Amphipolis on the Strymon river. Thasos, a member of the League, saw her interests in the mines of Mt. Pangaion threatened and defected from the League to Persia. She called to Sparta for assistance but was denied, as Sparta was facing the largest helot revolt in its history.
After more than two years of siege, Thasos surrendered to the Athenian leader Aristides and was forced back into the league. As a result, the fortification walls of Thasos were torn down, and they had to pay yearly tribute and fines. Additionally, their land, naval ships, and the mines of Thasos were confiscated by Athens. The siege of Thasos marks the transformation of the Delian league from an alliance into, in the words of Thucydides, a hegemony.
| 717 |
Delian League
| 3 |
2,037 |
# Delian League
## Policies of the League {#policies_of_the_league}
In 461 BC, Cimon was ostracized and was succeeded in his influence by democrats such as Ephialtes and Pericles. This signaled a complete change in Athenian foreign policy, neglecting the alliance with the Spartans and instead allying with her enemies, Argos and Thessaly. Megara deserted the Spartan-led Peloponnesian League and allied herself with Athens, allowing construction of a double line of walls across the Isthmus of Corinth and protecting Athens from attack from that quarter. Roughly a decade earlier, due to encouragement from influential speaker Themistocles, the Athenians had also constructed the Long Walls connecting their city to the Piraeus, its port, making it effectively invulnerable to attack by land.
In 454 BC, the Athenian general Pericles moved the Delian League\'s treasury from Delos to Athens, allegedly to keep it safe from Persia. However, Plutarch indicates that many of Pericles\'s rivals viewed the transfer to Athens as usurping monetary resources to fund elaborate building projects. Athens also switched from accepting ships, men and weapons as dues from league members, to only accepting money.
The new treasury established in Athens was used for many purposes, not all relating to the defence of members of the league. It was from tribute paid to the league that Pericles set to building the Parthenon on the Acropolis, replacing an older temple, as well as many other non-defense related expenditures. The Delian League was turning from an alliance into an empire.
## Wars against Persia {#wars_against_persia}
War with the Persians continued. In 460 BC, Egypt revolted under local leaders the Hellenes called Inaros and Amyrtaeus, who requested aid from Athens. Pericles led 250 ships, intended to attack Cyprus, to their aid because it would further damage Persia. After four years, however, the Egyptian rebellion was defeated by the Achaemenid general Megabyzus, who captured the greater part of the Athenian forces. In fact, according to Isocrates, the Athenians and their allies lost some 20,000 men in the expedition, while modern estimates place the figure at 50,000 men and 250 ships including reinforcements. The remainder escaped to Cyrene and thence returned home.
This was the Athenians\' main (public) reason for moving the treasury of the League from Delos to Athens, further consolidating their control over the League. The Persians followed up their victory by sending a fleet to re-establish their control over Cyprus, and 200 ships were sent out to counter them under Cimon, who returned from ostracism in 451 BC. He died during the blockade of Citium, though the fleet won a double victory by land and sea over the Persians off Salamis, Cyprus.
This battle was the last major one fought against the Persians. Many writers report that a peace treaty, known as the Peace of Callias, was formalized in 450 BC, but some writers believe that the treaty was a myth created later to inflate the stature of Athens. However, an understanding was definitely reached, enabling the Athenians to focus their attention on events in Greece proper.
| 502 |
Delian League
| 4 |
2,037 |
# Delian League
## Wars in Greece {#wars_in_greece}
Soon, war with the Peloponnesians broke out. In 458 BC, the Athenians blockaded the island of Aegina, and simultaneously defended Megara from the Corinthians by sending out an army composed of those too young or old for regular military service. The following year, Sparta sent an army into Boeotia, reviving the power of Thebes in order to help hold the Athenians in check. Their return was blocked, and they resolved to march on Athens, where the Long Walls were not yet completed, winning a victory at the Battle of Tanagra. All this accomplished, however, was to allow them to return home via the Megarid. Two months later, the Athenians under Myronides invaded Boeotia, and winning the Battle of Oenophyta gained control of the whole country except Thebes.
Reverses followed peace with Persia in 449 BC. The Battle of Coronea, in 447 BC, led to the abandonment of Boeotia. Euboea and Megara revolted, and while the former was restored to its status as a tributary ally, the latter was a permanent loss. The Delian and Peloponnesian Leagues signed a peace treaty, which was set to endure for thirty years. It only lasted until 431 BC, when the Peloponnesian War broke out.
Those who revolted unsuccessfully during the war saw the example made of the Mytilenians, the principal people on Lesbos. After an unsuccessful revolt, the Athenians ordered the death of the entire male population. After some thought, they rescinded this order, and only put to death the leading 1000 ringleaders of the revolt, and redistributed the land of the entire island to Athenian shareholders, who were sent out to reside on Lesbos.
This type of treatment was not reserved solely for those who revolted. Thucydides documents the example of Melos, a small island, neutral in the war, though founded by Spartans. The Melians were offered a choice to join the Athenians, or be conquered. Choosing to resist, their town was besieged and conquered; the males were put to death and the women sold into slavery (see Melian dialogue).
| 345 |
Delian League
| 5 |
2,037 |
# Delian League
## Athenian Empire (454--404 BC) {#athenian_empire_454404_bc}
By 454 BC, the Delian League could be fairly characterised as an Athenian Empire; a key event of 454 BC was the moving of the treasury of the Delian League from Delos to Athens. This is often seen as a key marker of the transition from alliance to empire, but while it is significant, it is important to view the period as a whole when considering the development of Athenian imperialism, and not to focus on a single event as being the main contributor to it. At the start of the Peloponnesian War, only Chios and Lesbos were left to contribute ships, and these states were by now far too weak to secede without support. Lesbos tried to revolt first, and failed completely. Chios, the most powerful of the original members of the Delian League save Athens, was the last to revolt, and in the aftermath of the Syracusan Expedition enjoyed success for several years, inspiring all of Ionia to revolt. Athens was nonetheless eventually able to suppress these revolts.
To further strengthen Athens\'s grip on its empire, Pericles in 450 BC began a policy of establishing *kleruchiai*---quasi-colonies that remained tied to Athens and which served as garrisons to maintain control of the League\'s vast territory. Furthermore, Pericles employed a number of offices to maintain Athens\' empire: *proxenoi*, who fostered good relations between Athens and League members; *episkopoi* and *archontes*, who oversaw the collection of tribute; and *hellenotamiai*, who received the tribute on Athens\' behalf.
Athens\'s empire was not very stable and after 27 years of war, the Spartans, aided by the Persians and Athenian internal strife, were able to defeat it. However, it did not remain defeated for long. The Second Athenian League, a maritime self-defense league, was founded in 377 BC and was led by Athens. The Athenians would never recover the full extent of their power, and their enemies were now far stronger and more varied
| 328 |
Delian League
| 6 |
2,038 |
# August Horch
**August Horch** (12 October 1868 -- 3 February 1951) was a German engineer and automobile pioneer, the founder of the manufacturing giant that eventually became Audi.
## Beginnings
Horch was born in Winningen, Rhenish Prussia. His initial trade was as a blacksmith, and then was educated at *italic=no* (Mittweida Technical College). After receiving a degree in engineering, he worked in shipbuilding. Horch worked for Karl Benz from 1896, before founding *A. Horch & Co.* in November 1899, in Ehrenfeld, Cologne, Germany.
## Manufacturing
The first Horch automobile was built in 1901. The company moved to Reichenbach in 1902 and Zwickau in 1904. Horch left the company in 1909 after a dispute, and set up in competition in Zwickau. His new firm was initially called *Horch Automobil-Werke GmbH*, but following a legal dispute over the *Horch* name, he decided to make another automobile company. (The court decided that *Horch* was a registered trademark on behalf of August\'s former partners and August was not entitled to use it any more). Consequently, Horch named his new company *Audi Automobilwerke GmbH* in 1910, *Audi* being the Latinization of Horch.
## Post Audi {#post_audi}
Horch left Audi in 1920 and went to Berlin and took various jobs. He published his autobiography, *I Built Cars (*Ich Baute Autos*)* in 1937. He also served on the board of Auto Union, the successor to Audi Automobilwerke GmbH he had founded. Horch remained an honorary executive at Auto Union during and after its reincorporation in Ingolstadt, Bavaria in the late 1940s until his death in 1951, ultimately not living to see the later resurrection of his Audi brand a decade later under the ownership of Volkswagen.
He was an honorary citizen of Zwickau and had a street named for his Audi cars in both Zwickau and his birthplace Winningen. He was made an honorary professor at Braunschweig University of Technology. There is an *August Horchstrasse* (August Horch Street) at Audi\'s main manufacturing plant in Ingolstadt
| 329 |
August Horch
| 0 |
2,039 |
# Avionics
**Avionics** (a portmanteau of *aviation* and *electronics*) are the electronic systems used on aircraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fitted to aircraft to perform individual functions. These can be as simple as a searchlight for a police helicopter or as complicated as the tactical system for an airborne early warning platform.
## History
The term \"avionics\" was coined in 1949 by Philip J. Klass, senior editor at *Aviation Week & Space Technology* magazine as a portmanteau of \"**aviation electronics**\".
Radio communication was first used in aircraft just prior to World War I. The first airborne radios were in zeppelins, but the military sparked development of light radio sets that could be carried by heavier-than-air craft, so that aerial reconnaissance biplanes could report their observations immediately in case they were shot down. The first experimental radio transmission from an airplane was conducted by the U.S. Navy in August 1910. The first aircraft radios transmitted by radiotelegraphy. They required a two-seat aircraft with a second crewman who operated a telegraph key to spell out messages in Morse code. During World War I, amplitude modulation voice two way radio sets were made possible in 1917 (see TM (triode)) by the development of the triode vacuum tube, which were simple enough that the pilot in a single seat aircraft could use it while flying.
Radar, the central technology used today in aircraft navigation and air traffic control, was developed by several nations, mainly in secret, as an air defense system in the 1930s during the runup to World War II. Many modern avionics have their origins in World War II wartime developments. For example, autopilot systems that are commonplace today began as specialized systems to help bomber planes fly steadily enough to hit precision targets from high altitudes. Britain\'s 1940 decision to share its radar technology with its U.S. ally, particularly the magnetron vacuum tube, in the famous Tizard Mission, significantly shortened the war. Modern avionics is a substantial portion of military aircraft spending. Aircraft like the F-15E and the now retired F-14 have roughly 20 percent of their budget spent on avionics. Most modern helicopters now have budget splits of 60/40 in favour of avionics.
The civilian market has also seen a growth in cost of avionics. Flight control systems (fly-by-wire) and new navigation needs brought on by tighter airspaces, have pushed up development costs. The major change has been the recent boom in consumer flying. As more people begin to use planes as their primary method of transportation, more elaborate methods of controlling aircraft safely in these high restrictive airspaces have been invented.
### Modern avionics {#modern_avionics}
Avionics plays a heavy role in modernization initiatives like the Federal Aviation Administration\'s (FAA) Next Generation Air Transportation System project in the United States and the Single European Sky ATM Research (SESAR) initiative in Europe. The Joint Planning and Development Office put forth a roadmap for avionics in six areas:
- Published Routes and Procedures -- Improved navigation and routing
- Negotiated Trajectories -- Adding data communications to create preferred routes dynamically
- Delegated Separation -- Enhanced situational awareness in the air and on the ground
- LowVisibility/CeilingApproach/Departure -- Allowing operations with weather constraints with less ground infrastructure
- Surface Operations -- To increase safety in approach and departure
- ATM Efficiencies -- Improving the air traffic management (ATM) process
### Market
The Aircraft Electronics Association reports \$1.73 billion avionics sales for the first three quarters of 2017 in business and general aviation, a 4.1% yearly improvement: 73.5% came from North America, forward-fit represented 42.3% while 57.7% were retrofits as the U.S. deadline of January 1, 2020 for mandatory ADS-B out approach.
| 622 |
Avionics
| 0 |
2,039 |
# Avionics
## Aircraft avionics {#aircraft_avionics}
The cockpit or, in larger aircraft, under the cockpit of an aircraft or in a movable nosecone, is a typical location for avionic bay equipment, including control, monitoring, communication, navigation, weather, and anti-collision systems. The majority of aircraft power their avionics using 14- or 28‑volt DC electrical systems; however, larger, more sophisticated aircraft (such as airliners or military combat aircraft) have AC systems operating at 115 volts 400 Hz, AC. There are several major vendors of flight avionics, including The Boeing Company, Panasonic Avionics Corporation, Honeywell (which now owns Bendix/King), Universal Avionics Systems Corporation, Rockwell Collins (now Collins Aerospace), Thales Group, GE Aviation Systems, Garmin, Raytheon, Parker Hannifin, UTC Aerospace Systems (now Collins Aerospace), Selex ES (now Leonardo), Shadin Avionics, and Avidyne Corporation.
International standards for avionics equipment are prepared by the Airlines Electronic Engineering Committee and published by ARINC.
### Avionics Installation {#avionics_installation}
Avionics installation is a critical aspect of modern aviation, ensuring that aircraft are equipped with the necessary electronic systems for safe and efficient operation. These systems encompass a wide range of functions, including communication, navigation, monitoring, flight control, and weather detection. Avionics installations are performed on all types of aircraft, from small general aviation planes to large commercial jets and military aircraft.
#### Installation Process {#installation_process}
The installation of avionics requires a combination of technical expertise, precision, and adherence to stringent regulatory standards. The process typically involves:
1. **Planning and Design**: Before installation, the avionics shop works closely with the aircraft owner to determine the required systems based on the aircraft type, intended use, and regulatory requirements. Custom instrument panels are often designed to accommodate the new systems.
2. **Wiring and Integration**: Avionics systems are integrated into the aircraft\'s electrical and control systems, with wiring often requiring laser marking for durability and identification. Shops use detailed schematics to ensure correct installation.
3. **Testing and Calibration**: After installation, each system must be thoroughly tested and calibrated to ensure proper function. This includes ground testing, flight testing, and system alignment with regulatory standards such as those set by the FAA.
4. **Certification**: Once the systems are installed and tested, the avionics shop completes the necessary certifications. In the U.S., this often involves compliance with FAA Part 91.411 and 91.413 for IFR (Instrument Flight Rules) operations, as well as RVSM (Reduced Vertical Separation Minimum) certification.
#### Regulatory Standards {#regulatory_standards}
Avionics installation is governed by strict regulatory frameworks to ensure the safety and reliability of aircraft systems. In the United States, the Federal Aviation Administration (FAA) sets the standards for avionics installations. These include guidelines for:
- **System Performance**: Avionics systems must meet performance benchmarks as defined by the FAA, ensuring they function correctly in all phases of flight.
- **Certification**: Shops performing installations must be FAA-certified, and their technicians often hold certifications such as the General Radiotelephone Operator License (GROL).
- **Inspections**: Aircraft equipped with newly installed avionics systems must undergo rigorous inspections before being cleared for flight, including both ground and flight tests.
#### Advancements in Avionics Technology {#advancements_in_avionics_technology}
The field of avionics has seen rapid technological advancements in recent years, leading to more integrated and automated systems. Key trends include:
- **Glass Cockpits**: Traditional analog gauges are being replaced by fully integrated glass cockpit displays, providing pilots with a centralized view of all flight parameters.
- **NextGen Technologies**: ADS-B and satellite-based navigation are part of the FAA\'s NextGen initiative, aimed at modernizing air traffic control and improving the efficiency of the national airspace.
- **Autonomous Systems**: Advanced automation systems are paving the way for more autonomous aircraft systems, enhancing safety, efficiency, and reducing pilot workload.
### Communications
Communications connect the flight deck to the ground and the flight deck to the passengers. On‑board communications are provided by public-address systems and aircraft intercoms.
The VHF aviation communication system works on the airband of 118.000 MHz to 136.975 MHz. Each channel is spaced from the adjacent ones by 8.33 kHz in Europe, 25 kHz elsewhere. VHF is also used for line of sight communication such as aircraft-to-aircraft and aircraft-to-ATC. Amplitude modulation is used, and the conversation is performed in simplex mode. Aircraft communication can also take place using HF (especially for trans-oceanic flights) or satellite communication.
### Navigation
Air navigation is the determination of position and direction on or above the surface of the Earth. Avionics can use satellite navigation systems (such as GPS and WAAS), inertial navigation system (INS), ground-based radio navigation systems (such as VOR or LORAN), or any combination thereof. Some navigation systems such as GPS calculate the position automatically and display it to the flight crew on moving map displays. Older ground-based Navigation systems such as VOR or LORAN requires a pilot or navigator to plot the intersection of signals on a paper map to determine an aircraft\'s location; modern systems calculate the position automatically and display it to the flight crew on moving map displays.
| 817 |
Avionics
| 1 |
2,039 |
# Avionics
## Aircraft avionics {#aircraft_avionics}
### Monitoring
The first hints of glass cockpits emerged in the 1970s when flight-worthy cathode-ray tube (CRT) screens began to replace electromechanical displays, gauges and instruments. A \"glass\" cockpit refers to the use of computer monitors instead of gauges and other analog displays. Aircraft were getting progressively more displays, dials and information dashboards that eventually competed for space and pilot attention. In the 1970s, the average aircraft had more than 100 cockpit instruments and controls. Glass cockpits started to come into being with the Gulfstream G‑IV private jet in 1985. One of the key challenges in glass cockpits is to balance how much control is automated and how much the pilot should do manually. Generally they try to automate flight operations while keeping the pilot constantly informed.
### Aircraft flight-control system {#aircraft_flight_control_system}
Aircraft have means of automatically controlling flight. Autopilot was first invented by Lawrence Sperry during World War I to fly bomber planes steady enough to hit accurate targets from 25,000 feet. When it was first adopted by the U.S. military, a Honeywell engineer sat in the back seat with bolt cutters to disconnect the autopilot in case of emergency. Nowadays most commercial planes are equipped with aircraft flight control systems in order to reduce pilot error and workload at landing or takeoff.
The first simple commercial auto-pilots were used to control heading and altitude and had limited authority on things like thrust and flight control surfaces. In helicopters, auto-stabilization was used in a similar way. The first systems were electromechanical. The advent of fly-by-wire and electro-actuated flight surfaces (rather than the traditional hydraulic) has increased safety. As with displays and instruments, critical devices that were electro-mechanical had a finite life. With safety critical systems, the software is very strictly tested.
### Fuel Systems {#fuel_systems}
Fuel Quantity Indication System (FQIS) monitors the amount of fuel aboard. Using various sensors, such as capacitance tubes, temperature sensors, densitometers & level sensors, the FQIS computer calculates the mass of fuel remaining on board.
Fuel Control and Monitoring System (FCMS) reports fuel remaining on board in a similar manner, but, by controlling pumps & valves, also manages fuel transfers around various tanks.
- Refuelling control to upload to a certain total mass of fuel and distribute it automatically.
- Transfers during flight to the tanks that feed the engines. E.G. from fuselage to wing tanks
- Centre of gravity control transfers from the tail (trim) tanks forward to the wings as fuel is expended
- Maintaining fuel in the wing tips (to alleviate wing bending due to lift in flight) & transferring to the main tanks after landing
- Controlling fuel jettison during an emergency to reduce the aircraft weight.
### Collision-avoidance systems {#collision_avoidance_systems}
To supplement air traffic control, most large transport aircraft and many smaller ones use a traffic alert and collision avoidance system (TCAS), which can detect the location of nearby aircraft, and provide instructions for avoiding a midair collision. Smaller aircraft may use simpler traffic alerting systems such as TPAS, which are passive (they do not actively interrogate the transponders of other aircraft) and do not provide advisories for conflict resolution.
To help avoid controlled flight into terrain (CFIT), aircraft use systems such as ground-proximity warning systems (GPWS), which use radar altimeters as a key element. One of the major weaknesses of GPWS is the lack of \"look-ahead\" information, because it only provides altitude above terrain \"look-down\". In order to overcome this weakness, modern aircraft use a terrain awareness warning system (TAWS).
### Flight recorders {#flight_recorders}
Commercial aircraft cockpit data recorders, commonly known as \"black boxes\", store flight information and audio from the cockpit. They are often recovered from an aircraft after a crash to determine control settings and other parameters during the incident.
### Weather systems {#weather_systems}
Weather systems such as weather radar (typically Arinc 708 on commercial aircraft) and lightning detectors are important for aircraft flying at night or in instrument meteorological conditions, where it is not possible for pilots to see the weather ahead. Heavy precipitation (as sensed by radar) or severe turbulence (as sensed by lightning activity) are both indications of strong convective activity and severe turbulence, and weather systems allow pilots to deviate around these areas.
Lightning detectors like the Stormscope or Strikefinder have become inexpensive enough that they are practical for light aircraft. In addition to radar and lightning detection, observations and extended radar pictures (such as NEXRAD) are now available through satellite data connections, allowing pilots to see weather conditions far beyond the range of their own in-flight systems. Modern displays allow weather information to be integrated with moving maps, terrain, and traffic onto a single screen, greatly simplifying navigation.
Modern weather systems also include wind shear and turbulence detection and terrain and traffic warning systems. In‑plane weather avionics are especially popular in Africa, India, and other countries where air-travel is a growing market, but ground support is not as well developed.
### Aircraft management systems {#aircraft_management_systems}
There has been a progression towards centralized control of the multiple complex systems fitted to aircraft, including engine monitoring and management. Health and usage monitoring systems (HUMS) are integrated with aircraft management computers to give maintainers early warnings of parts that will need replacement.
The integrated modular avionics concept proposes an integrated architecture with application software portable across an assembly of common hardware modules. It has been used in fourth generation jet fighters and the latest generation of airliners.
| 906 |
Avionics
| 2 |
2,039 |
# Avionics
## Mission or tactical avionics {#mission_or_tactical_avionics}
Military aircraft have been designed either to deliver a weapon or to be the eyes and ears of other weapon systems. The vast array of sensors available to the military is used for whatever tactical means required. As with aircraft management, the bigger sensor platforms (like the E‑3D, JSTARS, ASTOR, Nimrod MRA4, Merlin HM Mk 1) have mission-management computers.
Police and EMS aircraft also carry sophisticated tactical sensors.
### Military communications {#military_communications}
While aircraft communications provide the backbone for safe flight, the tactical systems are designed to withstand the rigors of the battle field. UHF, VHF Tactical (30--88 MHz) and SatCom systems combined with ECCM methods, and cryptography secure the communications. Data links such as Link 11, 16, 22 and BOWMAN, JTRS and even TETRA provide the means of transmitting data (such as images, targeting information etc.).
### Radar
Airborne radar was one of the first tactical sensors. The benefit of altitude providing range has meant a significant focus on airborne radar technologies. Radars include airborne early warning, anti-submarine warfare, and even weather radar (Arinc 708) and ground tracking/proximity radar.
The military uses radar in fast jets to help pilots fly at low levels. While the civil market has had weather radar for a while, there are strict rules about using it to navigate the aircraft.
### Sonar
Dipping sonar fitted to a range of military helicopters allows the helicopter to protect shipping assets from submarines or surface threats. Maritime support aircraft can drop active and passive sonar devices (sonobuoys) and these are also used to determine the location of enemy submarines.
### Electro-optics {#electro_optics}
Electro-optic systems include devices such as the head-up display (HUD), forward looking infrared (FLIR), infrared search and track and other passive infrared devices (Passive infrared sensor). These are all used to provide imagery and information to the flight crew. This imagery is used for everything from search and rescue to navigational aids and target acquisition.
### ESM/DAS
Electronic support measures and defensive aids systems are used extensively to gather information about threats or possible threats. They can be used to launch devices (in some cases automatically) to counter direct threats against the aircraft. They are also used to determine the state of a threat and identify it.
### Aircraft networks {#aircraft_networks}
The avionics systems in military, commercial and advanced models of civilian aircraft are interconnected using an avionics databus
| 402 |
Avionics
| 3 |
2,041 |
# Ares
**Ares** (`{{IPAc-en|ˈ|ɛər|iː|z}}`{=mediawiki}; *Ἄρης*, *Árēs* `{{IPA|el|árɛːs|}}`{=mediawiki}) is the Greek god of war and courage. He is one of the Twelve Olympians, and the son of Zeus and Hera. The Greeks were ambivalent towards him. He embodies the physical valor necessary for success in war but can also personify sheer brutality and bloodlust, in contrast to his sister Athena, whose martial functions include military strategy and generalship. An association with Ares endows places, objects, and other deities with a savage, dangerous, or militarized quality.
Although Ares\' name shows his origins as Mycenaean, his reputation for savagery was thought by some to reflect his likely origins as a Thracian deity. Some cities in Greece and several in Asia Minor held annual festivals to bind and detain him as their protector. In parts of Asia Minor, he was an oracular deity. Still further away from Greece, the Scythians were said to ritually kill one in a hundred prisoners of war as an offering to their equivalent of Ares. The later belief that ancient Spartans had offered human sacrifice to Ares may owe more to mythical prehistory, misunderstandings, and reputation than to reality.
Although there are many literary allusions to Ares\' love affairs and children, he has a limited role in Greek mythology. When he does appear, he is often humiliated. In the Trojan War, Aphrodite, protector of Troy, persuades Ares to take the Trojans\' side. The Trojans lose, while Ares\' sister Athena helps the Greeks to victory. Most famously, when the craftsman-god Hephaestus discovers his wife Aphrodite is having an affair with Ares, he traps the lovers in a net and exposes them to the ridicule of the other gods.
Ares\' nearest counterpart in Roman religion is Mars, who was given a more important and dignified place in ancient Roman religion as ancestral protector of the Roman people and state. During the Hellenization of Latin literature, the myths of Ares were reinterpreted by Roman writers under the name of Mars, and in later Western art and literature, the mythology of the two figures became virtually indistinguishable.
## Names
The etymology of the name *Ares* is traditionally connected with the Greek word *ἀρή* (*arē*), the Ionic form of the Doric *ἀρά* (*ara*), \"bane, ruin, curse, imprecation\". Walter Burkert notes that \"Ares is apparently an ancient abstract noun meaning throng of battle, war.\" R. S. P. Beekes has suggested a Pre-Greek origin of the name. The earliest attested form of the name is the Mycenaean Greek *𐀀𐀩}}*, *a-re*, written in the Linear B syllabic script.
The adjectival epithet, *Areios* (\"warlike\") was frequently appended to the names of other gods when they took on a warrior aspect or became involved in warfare: *Zeus Areios*, *Athena Areia*, even Aphrodite Areia (\"Aphrodite within Ares\" or \"feminine Ares\"), who was warlike, fully armoured and armed, partnered with Athena in Sparta, and represented at Kythira\'s temple to Aphrodite Urania. In the *Iliad*, the word *ares* is used as a common noun synonymous with \"battle\".
In the Classical period, Ares is given the epithet Enyalios, which seems to appear on the Mycenaean KN V 52 tablet as *𐀁𐀝𐀷𐀪𐀍}}*, *e-nu-wa-ri-jo*. Enyalios was sometimes identified with Ares and sometimes differentiated from him as another war god with separate cult, even in the same town; Burkert describes them as \"doubles almost\".
## Epithets
Source:
- **aatos** or **atos polemoio**, insatiate at war.
- **alloprosallos**, leaning first to one side, then to the other.
- **andreifontēs**, man-slaying.
- **apotimos**, dishonoured by Sophocles.
- **brotoloigos**, plague of man.
- **enyalios**, warlike.
- **Thēritas**, at Sparta. Laconic form of Thersites, audacious.
- **mainomenos**, malignant.
- **miaifonos**, blood-stained
- **tykton kakon**, complete evil.
| 606 |
Ares
| 0 |
2,041 |
# Ares
## Cult
In mainland Greece and the Peloponnese, only a few places are known to have had a formal temple and cult of Ares.`{{refn|group=n|Burkert lists temples at or near Troizen, Geronthrai and Halicarnassus. The Oxford Classical Dictionary adds Argos, Megalopolis, Therapne and Tegea in the Peloponnese, Athens and Erythrae, and Cretan sites Cnossus, Lato, Biannos and perhaps Olus.<ref name="OCD-Ares">{{cite book |last1=Graf |first1=Fritz |editor1-last=Hornblower & Spawforth |title=The Oxford Classical Dictionary |date=1996 |publisher=Oxford University Press |location=Oxford |isbn=019866172X |page=152 |edition=Third |chapter=Ares}}</ref>}}`{=mediawiki} Pausanias (2nd century AD) notes an altar to Ares at Olympia, and the moving of a Temple of Ares to the Athenian agora during the reign of Augustus, essentially rededicating it (2 AD) as a Roman temple to the Augustan Mars Ultor. The Areopagus (\"mount of Ares\"), a natural rock outcrop in Athens, some distance from the Acropolis, was supposedly where Ares was tried and acquitted by the gods for his revenge-killing of Poseidon\'s son, Halirrhothius, who had raped Ares\' daughter Alcippe. Its name was used for the court that met there, mostly to investigate and try potential cases of treason.
Numismatist M. Jessop Price states that Ares \"typified the traditional Spartan character\", but had no important cult in Sparta; and he never occurs on Spartan coins. Pausanias gives two examples of his cult, both of them conjointly with or \"within\" a warlike Aphrodite, on the Spartan acropolis. Gonzalez observes, in his 2005 survey of Ares\' cults in Asia Minor, that cults to Ares on the Greek mainland may have been more common than some sources assert. Wars between Greek states were endemic; war and warriors provided Ares\'s tribute, and fed his insatiable appetite for battle.
Ares\' attributes are instruments of war: a helmet, shield, and sword or spear. Libanius \"makes the apple sacred to Ares\", but \"offers no further comment\", nor connections to any aetiological myth. Apples are one of Aphrodites\' sacred or symbolic fruits. Littlewood follows Artemidorus claim that to dream of sour apples presages conflict, and lists Ares alongside Eris and the mythological \"Apples of Discord\".
### Chained statues {#chained_statues}
Gods were immortal but could be bound and restrained, both in mythic narrative and in cult practice. There was an archaic Spartan statue of Ares in chains in the temple of Enyalios (sometimes regarded as the son of Ares, sometimes as Ares himself), which Pausanias claimed meant that the spirit of war and victory was to be kept in the city.`{{refn|group=n|"Opposite this temple [the temple of Hipposthenes] is an old image of Enyalius in fetters. The idea the Lacedaemonians express by this image is the same as the Athenians express by their Wingless Victory; the former think that Enyalius will never run away from them, being bound in the fetters, while the Athenians think that Victory, having no wings, will always remain where she is".<ref>[[Pausanias (geographer)|Pausanias]], [http://data.perseus.org/citations/urn:cts:greekLit:tlg0525.tlg001.perseus-eng1:3.15.7 3.15.7].</ref>}}`{=mediawiki} The Spartans are known to have ritually bound the images of other deities, including Aphrodite and Artemis (cf Ares and Aphrodite bound by Hephaestus), and in other places there were chained statues of Artemis and Dionysos.
Statues of Ares in chains are described in the instructions given by an oracle of the late Hellenistic era to various cities of Pamphylia (in Anatolia) including Syedra, Lycia and Cilicia, places almost perpetually under threat from pirates. Each was told to set up a statue of \"bloody, man-slaying Ares\" and provide it with an annual festival in which it was ritually bound with iron fetters (\"by Dike and Hermes\") as if a supplicant for justice, put on trial and offered sacrifice. The oracle promises that \"thus will he become a peaceful deity for you, once he has driven the enemy horde far from your country, and he will give rise to prosperity much prayed for\". This Ares *karpodotes* (\"giver of Fruits\") is well attested in Lycia and Pisidia.
| 636 |
Ares
| 1 |
2,041 |
# Ares
## Cult
### Sacrifices
thumb\|upright=1.3\|Ares (right) with Demeter, Dionysus and Hermes on the frieze of the Parthenon, ca. 447--433 BC, British Museum.
Like most Greek deities, Ares was given animal sacrifice; in Sparta, after battle, he was given an ox for a victory by stratagem, or a rooster for victory through onslaught.`{{refn|group=n|Hughes is citing Plutarch, ''Instituta Laconica'' (trans. Babbit) Loeb, 1931, 25, 238F; "Whenever they overcome their enemies by out-generaling them, they sacrifice a bull to Ares, but when the victory is gained in open conflict, they offer a cock, thus trying to make their leaders habitually not merely fighters but tacticians as well". In ''The Life of Agesilaus'', 33.4: Plutarch claims that the Spartans thought victory was such ordinary work for them, they only sacrificed a rooster in recognition.}}`{=mediawiki} The usual recipient of sacrifice before battle was Athena. Reports of historic human sacrifice to Ares in an obscure rite known as the *Hekatomphonia* represent a very long-standing error, repeated through several centuries and well into the modern era.`{{refn|group=n|Among others, it has been repeated by ancient sources including [[Apollonius of Athens]], [[Pausanias (geographer)|Pausanias]], [[Porphyry (philosopher)|Porphyry]], [[Plutarch]], [[Clement of Alexandria]] and by many modern historians; see Hughes, "Human Sacrifice", 1991, pp.119-122 & notes 145, 146.}}`{=mediawiki} The *hekatomphonia* was an animal sacrifice to Zeus; it could be offered by any warrior who had personally slain one hundred of the enemy.`{{refn|group=n|In the [[Protrepticus (Clement)|Protrepticus]], Clement of Alexandria writes: "Indeed, [[Aristomenes|Aristomenes the Messenian]] sacrificed 300 men to Zeus of [[Ithome]]...[including] [[Theopompus]] the [[Lacedaemonian]] (Spartan) king, a noble victim." The rite was supposedly performed three times by Aristomenes: Plutarch did not find it credible that one man could have slaughtered three hundred. The Spartans claimed that Theopompus had only been wounded}}`{=mediawiki} Pausanias reports that in Sparta, each company of youths sacrificed a puppy to Enyalios before engaging in a hand-to-hand \"fight without rules\" at the Phoebaeum.`{{refn|group=n|"Here each company of youths sacrifices a puppy to Enyalius, holding that the most valiant of tame animals is an acceptable victim to the most valiant of the gods. I know of no other Greeks who are accustomed to sacrifice puppies except the people of [[Colophon (city)|Colophon]]; these too sacrifice a puppy, a black bitch, to the Wayside Goddess ([[Hecate]])".<ref>[[Pausanias (geographer)|Pausanias]], [http://data.perseus.org/citations/urn:cts:greekLit:tlg0525.tlg001.perseus-eng1:3.14.10 3.14.10].</ref>}}`{=mediawiki} The chthonic night-time sacrifice of a dog to Enyalios became assimilated to the cult of Ares. Porphyry claims, without detail, that Apollodorus of Athens (circa second century BC) says the Spartans made human sacrifices to Ares, but this may be a reference to mythic pre-history.
### Thrace and Scythia {#thrace_and_scythia}
A Thracian god identified by Herodotus (c. 484 -- c. 425 BC) as Ares, through *interpretatio Graeca*, was one of three otherwise unnamed deities that Thracian commoners were said to worship. Herodotus recognises and names the other two as \"Dionysus\" and \"Artemis\", and claims that the Thracian aristocracy exclusively worshiped \"Hermes\". In Herodotus\' *Histories*, the Scythians worship an indigenous form of Greek Ares, who is otherwise unnamed, but ranked beneath Tabiti (whom Herodotus claims as a form of Hestia), Api and Papaios in Scythia\'s divine hierarchy. His cult object was an iron sword. The \"Scythian Ares\" was offered blood-sacrifices (or ritual killings) of cattle, horses and \"one in every hundred human war-captives\", whose blood was used to douse the sword. Statues, and complex platform-altars made of heaped brushwood were devoted to him. This sword-cult, or one very similar, is said to have persisted among the Alans. Some have posited that the \"Sword of Mars\" in later European history alludes to the Huns having adopted Ares.
### Asia Minor {#asia_minor}
In some parts of Asia Minor, Ares was a prominent oracular deity, something not found in any Hellennic cult to Ares or Roman cult to Mars. Ares was linked in some regions or polities with a local god or cultic hero, and recognised as a higher, more prestigious deity than in mainland Greece. His cults in southern Asia Minor are attested from the 5th century BC and well into the later Roman Imperial era, at 29 different sites, and on over 70 local coin issues. He is sometimes represented on coinage of the region by the \"Helmet of Ares\" or carrying a spear and a shield, or as a fully armed warrior, sometimes accompanied by a female deity. In what is now western Turkey, the Hellenistic city of Metropolis built a monumental temple to Ares as the city\'s protector, not before the 3rd century BC. It is now lost, but the names of some of its priests and priestesses survive, along with the temple\'s likely depictions on coins of the province.
### Crete
A sanctuary of Aphrodite was established at Sta Lenika, on Crete, between the cities of Lato and Olus, possibly during the Geometric period. It was rebuilt in the late 2nd century BC as a double-sanctuary to Ares and Aphrodite. Inscriptions record disputes over the ownership of the sanctuary. The names of Ares and Aphrodite appear as witness to sworn oaths, and there is a Victory thanks-offering to Aphrodite, whom Millington believes had capacity as a \"warrior-protector acting in the realm of Ares\". There were cultic links between the Sta Lenika sanctuary, Knossos and other Cretan states, and perhaps with Argos on the mainland. While the Greek literary and artistic record from both the Archaic and Classical eras connects Ares and Aphrodite as complementary companions and ideal though adulterous lovers, their cult pairing and Aphrodite as warrior-protector is localised to Crete.
| 907 |
Ares
| 2 |
2,041 |
# Ares
## Cult
### Aksum
In Africa, Maḥrem, the principal god of the kings of Aksum prior to the 4th century AD, was invoked as Ares in Greek inscriptions. The anonymous king who commissioned the Monumentum Adulitanum in the late 2nd or early 3rd century refers to \"my greatest god, Ares, who also begat me, through whom I brought under my sway \[various peoples\]\". The monumental throne celebrating the king\'s conquests was itself dedicated to Ares. In the early 4th century, the last pagan king of Aksum, Ezana, referred to \"the one who brought me forth, the invincible Ares\".
| 100 |
Ares
| 3 |
2,041 |
# Ares
## Characterisation
Ares was one of the Twelve Olympians in the archaic tradition represented by the *Iliad* and *Odyssey.* In Greek literature, Ares often represents the physical or violent and untamed aspect of war and is the personification of sheer brutality and bloodlust (\"overwhelming, insatiable in battle, destructive, and man-slaughtering\", as Burkert puts it), in contrast to his sister, the armored Athena, whose functions as a goddess of intelligence include military strategy and generalship. An association with Ares endows places and objects with a savage, dangerous, or militarized quality; but when Ares does appear in myths, he typically faces humiliation.
In the *Iliad*, Zeus expresses a recurring Greek revulsion toward the god when Ares returns wounded and complaining from the battlefield at Troy: `{{poem quote|Then looking at him darkly Zeus who gathers the clouds spoke to him:
"Do not sit beside me and whine, you double-faced liar.
To me you are the most hateful of all gods who hold Olympus.
Forever quarrelling is dear to your heart, wars and battles.
...
And yet I will not long endure to see you in pain, since
you are my child, and it was to me that your mother bore you.
But were you born of some other god and proved so ruinous
long since you would have been dropped beneath the gods of the bright sky."<ref>''Iliad'', Book 5, lines 798–891, 895–898 in the translation of [[Richmond Lattimore]].</ref>}}`{=mediawiki}
This ambivalence is expressed also in the Greeks\' association of Ares with the Thracians, whom they regarded as a barbarous and warlike people. Thrace was considered to be Ares\'s birthplace and his refuge after the affair with Aphrodite was exposed to the general mockery of the other gods.`{{refn|group=n|Homer ''Odyssey'' viii. 361; for Ares/Mars and Thrace, see [[Ovid]], ''[[Ars Amatoria]]'', book ii.part xi.585, which tells the same tale: "Their captive bodies are, with difficulty, freed, at your plea, Neptune: Venus runs to Paphos: Mars heads for Thrace."; for Ares/Mars and Thrace, see also [[Statius]], ''Thebaid'' vii. 42}}`{=mediawiki}
A late 6th-century BC funerary inscription from Attica emphasizes the consequences of coming under Ares\'s sway:`{{poem quote|Stay and mourn at the tomb of dead Kroisos
Whom raging Ares destroyed one day, fighting in the foremost ranks.<ref>Athens, NM 3851 quoted in Andrew Stewart, ''One Hundred Greek Sculptors: Their Careers and Extant Works'', Introduction: I. "The Sources"</ref>}}`{=mediawiki}
| 388 |
Ares
| 4 |
2,041 |
# Ares
## Mythology
### Birth
He is one of the Twelve Olympians, and the son of Zeus and Hera.
### Argonautica
In the *Argonautica*, the *Golden Fleece* hangs in a grove sacred to Ares, until its theft by Jason. The Birds of Ares (*Ornithes Areioi*) drop feather darts in defense of the Amazons\' shrine to Ares, as father of their queen, on a coastal island in the Black Sea.
### Founding of Thebes {#founding_of_thebes}
Ares plays a central role in the founding myth of Thebes, as the progenitor of the water-dragon slain by Cadmus. The dragon\'s teeth were sown into the ground as if a crop and sprang up as the fully armored autochthonic Spartoi. Cadmus placed himself in the god\'s service for eight years to atone for killing the dragon. To further propitiate Ares, Cadmus married Harmonia, a daughter of Ares\'s union with Aphrodite. In this way, Cadmus harmonized all strife and founded the city of Thebes. In reality, Thebes came to dominate Boeotia\'s great and fertile plain, which in both history and myth was a battleground for competing polities. According to Plutarch, the plain was anciently described as \"The dancing-floor of Ares\".
### Aphrodite
In Homer\'s *Odyssey*, in the tale sung by the bard in the hall of Alcinous, the Sun-god Helios once spied Ares and Aphrodite having sex secretly in the hall of Hephaestus, her husband. Helios reported the incident to Hephaestus. Contriving to catch the illicit couple in the act, Hephaestus fashioned a finely-knitted and nearly invisible net with which to snare them. At the appropriate time, this net was sprung, and trapped Ares and Aphrodite locked in very private embrace.`{{refn|group=n|name="Odyssey, 8.295"|{{cite web | title = Odyssey, 8.295 | url = http://www.perseus.tufts.edu/hopper/text?doc=Hom.+Od.+8.&fromdoc=Perseus%3Atext%3A1999.01.0218 | quote = [In [[Robert Fagles]]'s translation]: ... and the two lovers, free of the bonds that overwhelmed them so, sprang up and away at once, and the Wargod sped Thrace, while Love with her telltale laughter sped to Paphos ...}}}}`{=mediawiki}
But Hephaestus was not satisfied with his revenge, so he invited the Olympian gods and goddesses to view the unfortunate pair. For the sake of modesty, the goddesses demurred, but the male gods went to witness the sight. Some commented on the beauty of Aphrodite, others remarked that they would eagerly trade places with Ares, but all who were present mocked the two. Once the couple was released, the embarrassed Ares returned to his homeland, Thrace, and Aphrodite went to Paphos.`{{refn|group=n|name="Odyssey, 8.295"}}`{=mediawiki}
In a much later interpolated detail, Ares put the young soldier Alectryon, who was Ares companion in drinking and even love-making, by his door to warn them of Helios\'s arrival as Helios would tell Hephaestus of Aphrodite\'s infidelity if the two were discovered, but Alectryon fell asleep on guard duty. Helios discovered the two and alerted Hephaestus. The furious Ares turned the sleepy Alectryon into a rooster which now always announces the arrival of the sun in the morning, as a way of apologizing to Ares.
The Chorus of Aeschylus\' *Suppliants* (written 463 BC) refers to Ares as Aphrodite\'s \"mortal-destroying bedfellow\". In the *Illiad*, Ares helps the Trojans because of his affection for their divine protector, Aphrodite; she thus redirects his innate destructive savagery to her own purposes.
### Giants
In one archaic myth, related only in the *Iliad* by the goddess Dione to her daughter Aphrodite, two chthonic giants, the Aloadae, named Otus and Ephialtes, bound Ares in chains and imprisoned him in a bronze urn, where he remained for thirteen months, a lunar year. \"And that would have been the end of Ares and his appetite for war, if the beautiful Eriboea, the young giants\' stepmother, had not told Hermes what they had done,\" she related. In this, \[Burkert\] suspects \"a festival of licence which is unleashed in the thirteenth month\". Ares was held screaming and howling in the urn until Hermes rescued him, and Artemis tricked the Aloadae into slaying each other.
In Nonnus\'s *Dionysiaca*, in the war between Cronus and Zeus, Ares killed an unnamed giant son of Echidna who was allied with Cronus, and described as spitting \"horrible poison\" and having \"snaky\" feet.
In some versions of the Gigantomachy, Ares was the god who killed the giant Mimas.
In the 2nd century AD *Metamorphoses* of Antoninus Liberalis, when the monstrous Typhon attacked Olympus the gods transformed into animals and fled to Egypt; Ares changed into a fish, the Lepidotus (sacred to the Egyptian war-god Anhur). Liberalis\'s koine Greek text is a \"completely inartistic\" epitome of Nicander\'s now lost *Heteroeumena* (2nd century BC).
### *Iliad*
In Homer\'s *Iliad*, Ares has no fixed allegiance. He promises Athena and Hera that he will fight for the Achaeans but Aphrodite persuades him to side with the Trojans. During the war, Diomedes fights Hector and sees Ares fighting on the Trojans\' side. Diomedes calls for his soldiers to withdraw. Zeus grants Athena permission to drive Ares from the battlefield. Encouraged by Hera and Athena, Diomedes thrusts with his spear at Ares. Athena drives the spear home, and all sides tremble at Ares\'s cries. Ares flees to Mount Olympus, forcing the Trojans to fall back. Ares overhears that his son Ascalaphus has been killed and wants to change sides again, rejoining the Achaeans for vengeance, disregarding Zeus\'s order that no Olympian should join the battle. Athena stops him. Later, when Zeus allows the gods to fight in the war again, Ares attacks Athena to avenge his previous injury. Athena overpowers him by striking him with a boulder.
| 916 |
Ares
| 5 |
2,041 |
# Ares
## Mythology
### Attendants
Deimos (\"Terror\" or \"Dread\") and Phobos (\"Fear\") are Ares\' companions in war, and according to Hesiod, are also his children by Aphrodite. Eris, the goddess of discord, or Enyo, the goddess of war, bloodshed, and violence, was considered the sister and companion of the violent Ares. In at least one tradition, Enyalius, rather than another name for Ares, was his son by Enyo.
Ares may also be accompanied by Kydoimos, the daemon of the din of battle; the Makhai (\"Battles\"); the \"Hysminai\" (\"Acts of manslaughter\"); Polemos, a minor spirit of war, or only an epithet of Ares, since it has no specific dominion; and Polemos\'s daughter, Alala, the goddess or personification of the Greek war-cry, whose name Ares uses as his own war-cry. Ares\'s sister Hebe (\"Youth\") also draws baths for him.
According to Pausanias, local inhabitants of Therapne, Sparta, recognized Thero, \"feral, savage\", as a nurse of Ares.
### Offspring and affairs {#offspring_and_affairs}
Though Ares plays a relatively limited role in Greek mythology as represented in literary narratives, his numerous love affairs and abundant offspring are often alluded to. The union of Ares and Aphrodite created the gods Eros, Anteros, Phobos, Deimos, and Harmonia. Other versions include Alcippe as one of their daughters.
Ares had a romantic liaison with Eos, the goddess of the dawn. Aphrodite discovered them, and in anger she cursed Eos with insatiable lust for men.
Cycnus (Κύκνος) of Macedonia was a mortal son of Ares who tried to build a temple to his father with the skulls and bones of guests and travellers. Heracles fought him and, in one account, killed him. In another account, Ares fought his son\'s killer but Zeus parted the combatants with a thunderbolt.
By a woman named Teirene he had a daughter named Thrassa, who in turn had a daughter named Polyphonte. Polyphonte was cursed by Aphrodite to love and mate with a bear, producing two sons, Agrius and Oreius, who were hubristic toward the gods and had a habit of eating their guests. Zeus sent Hermes to punish them, and he chose to chop off their hands and feet. Since Polyphonte was descended from him, Ares stopped Hermes, and the two brothers came into an agreement to turn Polyphonte\'s family into birds instead. Oreius became an eagle owl, Agrius a vulture, and Polyphonte a strix, possibly a small owl, certainly a portent of war; Polyphonte\'s servant prayed not to become a bird of evil omen and Ares and Hermes fulfilled her wish by choosing the woodpecker for her, a good omen for hunters.
#### List of offspring and their mothers {#list_of_offspring_and_their_mothers}
Sometimes poets and dramatists recounted ancient traditions, which varied, and sometimes they invented new details; later scholiasts might draw on either or simply guess. Thus while Phobos and Deimos were regularly described as offspring of Ares, others listed here such as Meleager, Sinope and Solymus were sometimes said to be children of Ares and sometimes given other fathers.
The following is a list of Ares\' offspring, by various mothers. Beside each offspring, the earliest source to record the parentage is given, along with the century to which the source dates.
Offspring Mother Source Date
--------------------- ----------------------- ------------------- ---------------------------------------- --
Phobos Aphrodite Hes. *Theog.* data-sort-value=1 \| 8th cent. BC
Deimos Hes. *Theog.* data-sort-value=1 \| 8th cent. BC
Harmonia Hes. *Theog.* data-sort-value=1 \| 8th cent. BC
Eros Simonides
Anteros Cic. *DND* data-sort-value=15 \| 1st cent. BC
Odomantus Calliope
Mygdon
Edonus
Biston Terpsichore *Etym. Mag.* data-sort-value=39 \| 12th cent. AD
Callirrhoe Steph. Byz. data-sort-value=27 \| 6th cent. AD
Enyalius Enyo
Dragon of Thebes Erinys of Telphusa
Nike *No mother mentioned* *HH* 8
Sinope (possibly) Aegina Schol. Ap. Rhod.
Edonus Callirrhoe Steph. Byz. data-sort-value=27 \| 6th cent. AD
Odomantus Steph. Byz. data-sort-value=27 \| 6th cent. AD
Cycnus Cleobula
Pelopia Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Pyrene Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Diomedes of Thrace Cyrene Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Crestone Tzetzes data-sort-value=39 \| 12th cent. AD
The Amazons Harmonia
Oenomaus Sterope Hyg. *Fab.* data-sort-value=17 \| 1st cent. AD
Harpina Diod. Sic. data-sort-value=15 \| 1st cent. BC
Eurythoe the Danaid Tzetzes data-sort-value=39 \| 12th cent. AD
Evenus Sterope Ps.-Plutarch
Demonice Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Thrassa Tereine Ant. Lib. data-sort-value=20 \| 2nd/3rd cent. AD
Melanippus Triteia Paus. data-sort-value=19 \| 2nd cent. AD
Aeropus Aerope Paus. data-sort-value=19 \| 2nd cent. AD
Alcippe Aglauros Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Meleager Althaea Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Calydon Astynome
Ascalaphus Astyoche Paus. data-sort-value=19 \| 2nd cent. AD
Ialmenus Paus. data-sort-value=19 \| 2nd cent. AD
Parthenopaeus Atalanta Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Solymus Caldene *Etym. Mag.* data-sort-value=39 \| 12th cent. AD
Phlegyas Chryse Paus. data-sort-value=19 \| 2nd cent. AD
Dotis Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Pangaeus Critobule Ps.-Plutarch
Molus, Pylus Demonice Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Thestius Pisidice Ps.-Plutarch
Demonice Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Stymphelus Dormothea Ps.-Plutarch
Antiope Otrera Hyg. *Fab.* data-sort-value=17 \| 1st cent. AD
Hippolyta Hyg. *Fab.* data-sort-value=17 \| 1st cent. AD
Melanippe
Penthesilea Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Sinope Parnassa Eumelus
Lycaon Pyrene
Lycastus Phylonome Ps.-Plutarch
Parrhasius Ps.-Plutarch
Oxylus Protogeneia Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Bithys Sete
Tmolus Theogone Ps.-Plutarch
Ismarus Thracia
Alcon of Thrace *No mother mentioned* Hyg. *Fab.* data-sort-value=17 \| 1st cent. AD
Chalyps
Cheimarrhoos Schol. Hes., *WD*
Dryas Apollod. data-sort-value=18 \| 1st/2nd cent. AD
Hyperbius
Lycus of Libya
Nisos Hyg. *Fab.* data-sort-value=17 \| 1st cent. AD
Oeagrus Nonnus data-sort-value=25 \| 5th cent. AD
Paeon *Etym. Mag.* data-sort-value=39 \| 12th cent. AD
Portheus (Porthaon) Ant. Lib. data-sort-value=20 \| 2nd/3rd cent. AD
Tereus Apollod. data-sort-value=18 \| 1st/2nd cent. AD
## Mars
The nearest counterpart of Ares among the Roman gods is Mars, a son of Jupiter and Juno, pre-eminent among the Roman army\'s military gods but originally an agricultural deity. As a father of Romulus, Rome\'s legendary founder, Mars was given an important and dignified place in ancient Roman religion, as a guardian deity of the entire Roman state and its people. Under the influence of Greek culture, Mars was identified with Ares, but the character and dignity of the two deities differed fundamentally. Mars was represented as a means to secure peace, and he was a father *(pater)* of the Roman people. In one tradition, he fathered Romulus and Remus through his rape of Rhea Silvia. In another, his lover, the goddess Venus, gave birth to Aeneas, the Trojan prince and refugee who \"founded\" Rome several generations before Romulus.
In the Hellenization of Latin literature, the myths of Ares were reinterpreted by Roman writers under the name of Mars. Greek writers under Roman rule also recorded cult practices and beliefs pertaining to Mars under the name of Ares. Thus in the classical tradition of later Western art and literature, the mythology of the two figures later became virtually indistinguishable.
| 1,136 |
Ares
| 6 |
2,041 |
# Ares
## Renaissance and later depictions {#renaissance_and_later_depictions}
In Renaissance and Neoclassical works of art, Ares\'s symbols are a spear and helmet, his animal is a dog, and his bird is the vulture. In literary works of these eras, Ares is replaced by the Roman Mars, a romantic emblem of manly valor rather than the cruel and blood-thirsty god of Greek mythology
| 62 |
Ares
| 7 |
2,049 |
# Alpha compositing
In computer graphics, **alpha compositing** or **alpha blending** is the process of combining one image with a background to create the appearance of partial or full transparency. It is often useful to render picture elements (pixels) in separate passes or layers and then combine the resulting 2D images into a single, final image called the composite. Compositing is used extensively in film when combining computer-rendered image elements with live footage. Alpha blending is also used in 2D computer graphics to put rasterized foreground elements over a background.
In order to combine the picture elements of the images correctly, it is necessary to keep an associated *matte* for each element in addition to its color. This matte layer contains the coverage information---the shape of the geometry being drawn---making it possible to distinguish between parts of the image where something was drawn and parts that are empty.
Although the most basic operation of combining two images is to put one over the other, there are many operations, or blend modes, that are used.
## History
The concept of an alpha channel was introduced by Alvy Ray Smith and Ed Catmull in the late 1970s at the New York Institute of Technology Computer Graphics Lab. Bruce A. Wallace derived the same straight **over** operator based on a physical reflectance/transmittance model in 1981. A 1984 paper by Thomas Porter and Tom Duff introduced premultiplied alpha using a geometrical approach.
The use of the term *alpha* is explained by Smith as follows: \"We called it that because of the classic linear interpolation formula $\alpha A + (1-\alpha)B$ that uses the Greek letter $\alpha$ (alpha) to control the amount of interpolation between, in this case, two images A and B\". That is, when compositing image A atop image B, the value of $\alpha$ in the formula is taken directly from A\'s alpha channel.
| 310 |
Alpha compositing
| 0 |
2,049 |
# Alpha compositing
## Description
In a 2D image a color combination is stored for each picture element (pixel), often a combination of red, green and blue (RGB). When alpha compositing is in use, each pixel has an additional numeric value stored in its **alpha channel**, with a value ranging from 0 to 1. A value of 0 means that the pixel is fully transparent and the color in the pixel beneath will show through. A value of 1 means that the pixel is fully opaque.
With the existence of an alpha channel, it is possible to express compositing image operations using a *compositing algebra*. For example, given two images *A* and *B*, the most common compositing operation is to combine the images so that *A* appears in the foreground and *B* appears in the background. This can be expressed as *A* **over** *B*. In addition to **over**, Porter and Duff defined the compositing operators **in**, **held out by** (the phrase refers to holdout matting and is usually abbreviated **out**), **atop**, and **xor** (and the reverse operators **rover**, **rin**, **rout**, and **ratop**) from a consideration of choices in blending the colors of two pixels when their coverage is, conceptually, overlaid orthogonally:
As an example, the **over** operator can be accomplished by applying the following formula to each pixel:
$$\begin{align}\alpha_o &= \phantom{~C_a}\alpha_a + \phantom{C_b}\alpha_b(1 - \alpha_a) \\
C_o &= \frac{ C_a \alpha_a + C_b \alpha_b (1 - \alpha_a) }{\alpha_o}
\end{align}$$
Here $C_o$, $C_a$ and $C_b$ stand for the color components of the pixels in the result of the \"over\", image A, and image B respectively, applied to each color channel (red/green/blue) individually, whereas $\alpha_o$, $\alpha_a$ and $\alpha_b$ are the alpha values of the respective pixels.
The **over** operator is, in effect, the normal painting operation (see Painter\'s algorithm). The **in** and **out** operators are the alpha compositing equivalent of clipping. The two use only the alpha channel of the second image and ignore the color components. In addition, **plus** defines additive blending.
| 331 |
Alpha compositing
| 1 |
2,049 |
# Alpha compositing
## Straight versus premultiplied {#straight_versus_premultiplied}
If an alpha channel is used in an image, there are two common representations that are available: straight (unassociated) alpha and premultiplied (associated) alpha.
- With **straight alpha**, the RGB components represent the color of the object or pixel, disregarding its opacity. This is the method implied by the **over** operator in the previous section.
- With **premultiplied alpha**, the RGB components represent the emission of the object or pixel, and the alpha represents the occlusion. The **over** operator then becomes:
$$C_o = C_a + C_b(1 - \alpha_a)$$
$$\alpha_o = \alpha_a + \alpha_b(1 - \alpha_a)$$
### Comparison
The most significant advantage of premultiplied alpha is that it allows for correct blending, interpolation, and filtering. Ordinary interpolation without premultiplied alpha leads to RGB information leaking out of fully transparent (A=0) regions, even though this RGB information is ideally invisible. When interpolating or filtering images with abrupt borders between transparent and opaque regions, this can result in borders of colors that were not visible in the original image. Errors also occur in areas of semitransparency because the RGB components are not correctly weighted, giving incorrectly high weighting to the color of the more transparent (lower alpha) pixels.
Premultiplied alpha may also be used to allow regions of regular alpha blending (e.g. smoke) and regions with additive blending mode (e.g. flame and glitter effects) to be encoded within the same image. This is represented by an RGBA triplet that express emission with no occlusion, such as (0.4, 0.3, 0.2, 0.0).
Another advantage of premultiplied alpha is performance; in certain situations, it can reduce the number of multiplication operations (e.g. if the image is used many times during later compositing). The Porter--Duff operations have a simple form only in premultiplied alpha. Some rendering pipelines expose a \"straight alpha\" API surface, but converts them into premultiplied alpha for performance.
One disadvantage of premultiplied alpha is that it can reduce the available relative precision in the RGB values when using integer or fixed-point representation for the color components. This may cause a noticeable loss of quality if the color information is later brightened or if the alpha channel is removed. In practice, this is not usually noticeable because during typical composition operations, such as OVER, the influence of the low-precision color information in low-alpha areas on the final output image (after composition) is correspondingly reduced. This loss of precision also makes premultiplied images easier to compress using certain compression schemes, as they do not record the color variations hidden inside transparent regions, and can allocate fewer bits to encode low-alpha areas. The same "limitations" of lower quantisation bit depths such as 8 bit per channel are also present in imagery without alpha, and this argument is problematic as a result.
### Examples
Assuming that the pixel color is expressed using *straight* (non-premultiplied) RGBA tuples, a pixel value of (0, 0.7, 0, 0.5) implies a pixel that has 70% of the maximum green intensity and 50% opacity. If the color were fully green, its RGBA would be (0, 1, 0, 0.5). However, if this pixel uses premultiplied alpha, all of the RGB values (0, 0.7, 0) are multiplied, or scaled for occlusion, by the alpha value 0.5, which is appended to yield (0, 0.35, 0, 0.5). In this case, the 0.35 value for the G channel actually indicates 70% green emission intensity (with 50% occlusion). A pure green emission would be encoded as (0, 0.5, 0, 0.5). Knowing whether a file uses straight or premultiplied alpha is essential to correctly process or composite it, as a different calculation is required.
Emission with no occlusion cannot be represented in straight alpha. No conversion is available in this case.
| 618 |
Alpha compositing
| 2 |
2,049 |
# Alpha compositing
## Image formats supporting alpha channels {#image_formats_supporting_alpha_channels}
The most popular image formats that support the alpha channel are PNG and TIFF. GIF supports alpha channels, but is considered to be inefficient when it comes to file size. Support for alpha channels is present in some video codecs, such as Animation and Apple ProRes 4444 of the QuickTime format, or in the Techsmith multi-format codec.
The file format BMP generally does not support this channel; however, in different formats such as 32-bit (888--8) or 16-bit (444--4) it is possible to save the alpha channel, although not all systems or programs are able to read it: it is exploited mainly in some video games or particular applications; specific programs have also been created for the creation of these BMPs.
File/Codec format Maximum Depth Type Browser support Media type Notes
------------------------------------- --------------- ---------- --------------------- --------------- ------------------------------------------------------------------------------------------------------------------------------------------------
Apple ProRes 4444 16-bit None Video (.mov) ProRes is the successor of the Apple Intermediate Codec
HEVC / h.265 10-bit Limited to Safari Video (.hevc) Intended successor to H.264
WebM (codec video VP8, VP9, or AV1) 12-bit All modern browsers Video (.webm) While VP8/VP9 is widely supported with modern browsers, AV1 still has limited support. Only Chromium-based browsers will display alpha layers.
OpenEXR 32-bit None Image (.exr) Has largest HDR spread.
PNG 16-bit straight All modern browsers Image (.png)
APNG 24-bit straight Moderate support Image (.apng) Supports animation.
TIFF 32-bit both None Image (.tiff)
GIF 8-bit All modern browsers Image (.gif) Browsers generally do not support GIF alpha layers.
SVG 32-bit straight All modern browsers Image (.svg) Based on CSS color.
JPEG XL 32-bit both Moderate support Image (.jxl) Allows lossy and HDR.
| 279 |
Alpha compositing
| 3 |
2,049 |
# Alpha compositing
## Gamma correction {#gamma_correction}
The RGB values of typical digital images do not directly correspond to the physical light intensities, but are rather compressed by a gamma correction function:
: $C_\text{encoded} = C_\text{linear}^{1/\gamma}$
This transformation better utilizes the limited number of bits in the encoded image by choosing $\gamma$ that better matches the non-linear human perception of luminance.
Accordingly, computer programs that deal with such images must decode the RGB values into a linear space (by undoing the gamma-compression), blend the linear light intensities, and re-apply the gamma compression to the result:`{{Failed verification|date=October 2022}}`{=mediawiki}
: *$$C_o = \\left(\\frac{ C_a\^\\gamma \\alpha_a + C_b\^\\gamma \\alpha_b (1 - \\alpha_a) }{\\alpha_o}\\right)\^{1/\\gamma}*
When combined with premultiplied alpha, pre-multiplication is done in linear space, prior to gamma compression. This results in the following formula:
$$C_o = \left( C_a^\gamma + C_b^\gamma (1 - \alpha_a) \right)^{1/\gamma}$$
Note that the alpha channel may or may not undergo gamma-correction, even when the color channels do.
## Other transparency methods {#other_transparency_methods}
Although used for similar purposes, transparent colors and image masks do not permit the smooth blending of the superimposed image pixels with those of the background (only whole image pixels or whole background pixels allowed).
A similar effect can be achieved with a 1-bit alpha channel, as found in the 16-bit RGBA high color mode of the Truevision TGA image file format and related TARGA and AT-Vista/NU-Vista display adapters\' high color graphic mode. This mode devotes 5 bits for every primary RGB color (15-bit RGB) plus a remaining bit as the \"alpha channel\".
Dithering can be used to simulate partial occlusion where only 1-bit alpha is available.
For some applications, a single alpha channel is not sufficient: a stained-glass window, for instance, requires a separate transparency channel for each RGB channel to model the red, green and blue transparency separately. More alpha channels can be added for accurate spectral color filtration applications.
Some order-independent transparency methods replace the **over** operator with a commutative approximation
| 327 |
Alpha compositing
| 4 |
2,052 |
# Array (data structure)
In computer science, an **array** is a data structure consisting of a collection of *elements* (values or variables), of same memory size, each identified by at least one *array index* or *key*, a collection of which may be a tuple, known as an index tuple. An array is stored such that the position (memory address) of each element can be computed from its index tuple by a mathematical formula. The simplest type of data structure is a linear array, also called a one-dimensional array.
For example, an array of ten 32-bit (4-byte) integer variables, with indices 0 through 9, may be stored as ten words at memory addresses 2000, 2004, 2008, \..., 2036, (in hexadecimal: `0x7D0`, `0x7D4`, `0x7D8`, \..., `0x7F4`) so that the element with index *i* has the address 2000 + (*i* × 4). The memory address of the first element of an array is called first address, foundation address, or base address.
Because the mathematical concept of a matrix can be represented as a two-dimensional grid, two-dimensional arrays are also sometimes called \"matrices\". In some cases the term \"vector\" is used in computing to refer to an array, although tuples rather than vectors are the more mathematically correct equivalent. Tables are often implemented in the form of arrays, especially lookup tables; the word \"table\" is sometimes used as a synonym of array.
Arrays are among the oldest and most important data structures, and are used by almost every program. They are also used to implement many other data structures, such as lists and strings. They effectively exploit the addressing logic of computers. In most modern computers and many external storage devices, the memory is a one-dimensional array of words, whose indices are their addresses. Processors, especially vector processors, are often optimized for array operations.
Arrays are useful mostly because the element indices can be computed at run time. Among other things, this feature allows a single iterative statement to process arbitrarily many elements of an array. For that reason, the elements of an array data structure are required to have the same size and should use the same data representation. The set of valid index tuples and the addresses of the elements (and hence the element addressing formula) are usually, but not always, fixed while the array is in use.
The term \"array\" may also refer to an array data type, a kind of data type provided by most high-level programming languages that consists of a collection of values or variables that can be selected by one or more indices computed at run-time. Array types are often implemented by array structures; however, in some languages they may be implemented by hash tables, linked lists, search trees, or other data structures.
The term is also used, especially in the description of algorithms, to mean associative array or \"abstract array\", a theoretical computer science model (an abstract data type or ADT) intended to capture the essential properties of arrays.
## History
The first digital computers used machine-language programming to set up and access array structures for data tables, vector and matrix computations, and for many other purposes. John von Neumann wrote the first array-sorting program (merge sort) in 1945, during the building of the first stored-program computer. Array indexing was originally done by self-modifying code, and later using index registers and indirect addressing. Some mainframes designed in the 1960s, such as the Burroughs B5000 and its successors, used memory segmentation to perform index-bounds checking in hardware.
Assembly languages generally have no special support for arrays, other than what the machine itself provides. The earliest high-level programming languages, including FORTRAN (1957), Lisp (1958), COBOL (1960), and ALGOL 60 (1960), had support for multi-dimensional arrays, and so has C (1972). In C++ (1983), class templates exist for multi-dimensional arrays whose dimension is fixed at runtime as well as for runtime-flexible arrays.
## Applications
Arrays are used to implement mathematical vectors and matrices, as well as other kinds of rectangular tables. Many databases, small and large, consist of (or include) one-dimensional arrays whose elements are records.
Arrays are used to implement other data structures, such as lists, heaps, hash tables, deques, queues, stacks, strings, and VLists. Array-based implementations of other data structures are frequently simple and space-efficient (implicit data structures), requiring little space overhead, but may have poor space complexity, particularly when modified, compared to tree-based data structures (compare a sorted array to a search tree).
One or more large arrays are sometimes used to emulate in-program dynamic memory allocation, particularly memory pool allocation. Historically, this has sometimes been the only way to allocate \"dynamic memory\" portably.
Arrays can be used to determine partial or complete control flow in programs, as a compact alternative to (otherwise repetitive) multiple `IF` statements. They are known in this context as control tables and are used in conjunction with a purpose-built interpreter whose control flow is altered according to values contained in the array. The array may contain subroutine pointers (or relative subroutine numbers that can be acted upon by SWITCH statements) that direct the path of the execution.
| 846 |
Array (data structure)
| 0 |
2,052 |
# Array (data structure)
## Element identifier and addressing formulas {#element_identifier_and_addressing_formulas}
When data objects are stored in an array, individual objects are selected by an index that is usually a non-negative scalar integer. Indexes are also called subscripts. An index *maps* the array value to a stored object.
There are three ways in which the elements of an array can be indexed:
0 (*zero-based indexing*): The first element of the array is indexed by subscript of 0.{{cite web
`| access-date = 8 April 2011`\
`| publisher = Computer Programming Web programming Tips`\
`| title = Array Code Examples - PHP Array Functions - PHP code`\
`| quote = In most computer languages array index (counting) starts from 0, not from 1. Index of the first element of the array is 0, index of the second element of the array is 1, and so on. In array of names below you can see indexes and values.`\
`| url = `[`http://www.configure-all.com/arrays.php`](http://www.configure-all.com/arrays.php)\
`| archive-url = `[`https://web.archive.org/web/20110413142103/http://www.configure-all.com/arrays.php`](https://web.archive.org/web/20110413142103/http://www.configure-all.com/arrays.php)\
`| archive-date = 13 April 2011`\
`| url-status = dead`
}}
1 (*one-based indexing*): The first element of the array is indexed by subscript of 1.\
n (*n-based indexing*): The base index of an array can be freely chosen. Usually programming languages allowing *n-based indexing* also allow negative index values and other scalar data types like enumerations, or characters may be used as an array index.
Using zero based indexing is the design choice of many influential programming languages, including C, Java and Lisp. This leads to simpler implementation where the subscript refers to an offset from the starting position of an array, so the first element has an offset of zero.
Arrays can have multiple dimensions, thus it is not uncommon to access an array using multiple indices. For example, a two-dimensional array `A` with three rows and four columns might provide access to the element at the 2nd row and 4th column by the expression `A[1][3]` in the case of a zero-based indexing system. Thus two indices are used for a two-dimensional array, three for a three-dimensional array, and *n* for an *n*-dimensional array.
The number of indices needed to specify an element is called the dimension, dimensionality, or rank of the array.
In standard arrays, each index is restricted to a certain range of consecutive integers (or consecutive values of some enumerated type), and the address of an element is computed by a \"linear\" formula on the indices.
### One-dimensional arrays {#one_dimensional_arrays}
A one-dimensional array (or single dimension array) is a type of linear array. Accessing its elements involves a single subscript which can either represent a row or column index.
As an example consider the C declaration `int anArrayName[10];` which declares a one-dimensional array of ten integers. Here, the array can store ten elements of type `int` . This array has indices starting from zero through nine. For example, the expressions `anArrayName[0]` and `anArrayName[9]` are the first and last elements respectively.
For a vector with linear addressing, the element with index *i* is located at the address `{{nowrap|''B'' + ''c'' · ''i''}}`{=mediawiki}, where *B* is a fixed *base address* and *c* a fixed constant, sometimes called the *address increment* or *stride*.
If the valid element indices begin at 0, the constant *B* is simply the address of the first element of the array. For this reason, the C programming language specifies that array indices always begin at 0; and many programmers will call that element \"zeroth\" rather than \"first\".
However, one can choose the index of the first element by an appropriate choice of the base address *B*. For example, if the array has five elements, indexed 1 through 5, and the base address *B* is replaced by `{{nowrap|''B'' + 30''c''}}`{=mediawiki}, then the indices of those same elements will be 31 to 35. If the numbering does not start at 0, the constant *B* may not be the address of any element.
### Multidimensional arrays {#multidimensional_arrays}
For a multidimensional array, the element with indices *i*,*j* would have address *B* + *c* · *i* + *d* · *j*, where the coefficients *c* and *d* are the *row* and *column address increments*, respectively.
More generally, in a *k*-dimensional array, the address of an element with indices *i*~1~, *i*~2~, \..., *i*~*k*~ is
: *B* + *c*~1~ · *i*~1~ + *c*~2~ · *i*~2~ + ... + *c*~*k*~ · *i*~*k*~.
For example: int a\[2\]\[3\];
This means that array a has 2 rows and 3 columns, and the array is of integer type. Here we can store 6 elements they will be stored linearly but starting from first row linear then continuing with second row. The above array will be stored as a~11~, a~12~, a~13~, a~21~, a~22~, a~23~.
This formula requires only *k* multiplications and *k* additions, for any array that can fit in memory. Moreover, if any coefficient is a fixed power of 2, the multiplication can be replaced by bit shifting.
The coefficients *c*~*k*~ must be chosen so that every valid index tuple maps to the address of a distinct element.
If the minimum legal value for every index is 0, then *B* is the address of the element whose indices are all zero. As in the one-dimensional case, the element indices may be changed by changing the base address *B*. Thus, if a two-dimensional array has rows and columns indexed from 1 to 10 and 1 to 20, respectively, then replacing *B* by `{{nowrap|''B'' + ''c''<sub>1</sub> − 3''c''<sub>2</sub>}}`{=mediawiki} will cause them to be renumbered from 0 through 9 and 4 through 23, respectively. Taking advantage of this feature, some languages (like FORTRAN 77) specify that array indices begin at 1, as in mathematical tradition while other languages (like Fortran 90, Pascal and Algol) let the user choose the minimum value for each index.
### Dope vectors {#dope_vectors}
The addressing formula is completely defined by the dimension *d*, the base address *B*, and the increments *c*~1~, *c*~2~, \..., *c*~*k*~. It is often useful to pack these parameters into a record called the array\'s descriptor, stride vector, or dope vector. The size of each element, and the minimum and maximum values allowed for each index may also be included in the dope vector. The dope vector is a complete handle for the array, and is a convenient way to pass arrays as arguments to procedures. Many useful array slicing operations (such as selecting a sub-array, swapping indices, or reversing the direction of the indices) can be performed very efficiently by manipulating the dope vector.
| 1,076 |
Array (data structure)
| 1 |
2,052 |
# Array (data structure)
## Element identifier and addressing formulas {#element_identifier_and_addressing_formulas}
### Compact layouts {#compact_layouts}
Often the coefficients are chosen so that the elements occupy a contiguous area of memory. However, that is not necessary. Even if arrays are always created with contiguous elements, some array slicing operations may create non-contiguous sub-arrays from them.
There are two systematic compact layouts for a two-dimensional array. For example, consider the matrix
$$A =
\begin{bmatrix}
1 & 2 & 3 \\
4 & 5 & 6 \\
7 & 8 & 9
\end{bmatrix}.$$
In the row-major order layout (adopted by C for statically declared arrays), the elements in each row are stored in consecutive positions and all of the elements of a row have a lower address than any of the elements of a consecutive row:
: {\| class=\"wikitable\"
\|- \| 1 \|\| 2 \|\| 3 \|\| 4 \|\| 5 \|\| 6 \|\| 7 \|\| 8 \|\| 9 \|}
In column-major order (traditionally used by Fortran), the elements in each column are consecutive in memory and all of the elements of a column have a lower address than any of the elements of a consecutive column:
: {\| class=\"wikitable\"
\|- \| 1 \|\| 4 \|\| 7 \|\| 2 \|\| 5 \|\| 8 \|\| 3 \|\| 6 \|\| 9 \|}
For arrays with three or more indices, \"row major order\" puts in consecutive positions any two elements whose index tuples differ only by one in the *last* index. \"Column major order\" is analogous with respect to the *first* index.
In systems which use processor cache or virtual memory, scanning an array is much faster if successive elements are stored in consecutive positions in memory, rather than sparsely scattered. This is known as spatial locality, which is a type of locality of reference. Many algorithms that use multidimensional arrays will scan them in a predictable order. A programmer (or a sophisticated compiler) may use this information to choose between row- or column-major layout for each array. For example, when computing the product *A*·*B* of two matrices, it would be best to have *A* stored in row-major order, and *B* in column-major order.
### Resizing
Static arrays have a size that is fixed when they are created and consequently do not allow elements to be inserted or removed. However, by allocating a new array and copying the contents of the old array to it, it is possible to effectively implement a *dynamic* version of an array; see dynamic array. If this operation is done infrequently, insertions at the end of the array require only amortized constant time.
Some array data structures do not reallocate storage, but do store a count of the number of elements of the array in use, called the count or size. This effectively makes the array a dynamic array with a fixed maximum size or capacity; Pascal strings are examples of this.
### Non-linear formulas {#non_linear_formulas}
More complicated (non-linear) formulas are occasionally used. For a compact two-dimensional triangular array, for instance, the addressing formula is a polynomial of degree 2.
| 508 |
Array (data structure)
| 2 |
2,052 |
# Array (data structure)
## Efficiency
Both *store* and *select* take (deterministic worst case) constant time. Arrays take linear (O(*n*)) space in the number of elements *n* that they hold.
In an array with element size *k* and on a machine with a cache line size of B bytes, iterating through an array of *n* elements requires the minimum of ceiling(*nk*/B) cache misses, because its elements occupy contiguous memory locations. This is roughly a factor of B/*k* better than the number of cache misses needed to access *n* elements at random memory locations. As a consequence, sequential iteration over an array is noticeably faster in practice than iteration over many other data structures, a property called locality of reference (this does *not* mean however, that using a perfect hash or trivial hash within the same (local) array, will not be even faster - and achievable in constant time). Libraries provide low-level optimized facilities for copying ranges of memory (such as memcpy) which can be used to move contiguous blocks of array elements significantly faster than can be achieved through individual element access. The speedup of such optimized routines varies by array element size, architecture, and implementation.
Memory-wise, arrays are compact data structures with no per-element overhead. There may be a per-array overhead (e.g., to store index bounds) but this is language-dependent. It can also happen that elements stored in an array require *less* memory than the same elements stored in individual variables, because several array elements can be stored in a single word; such arrays are often called *packed* arrays. An extreme (but commonly used) case is the bit array, where every bit represents a single element. A single octet can thus hold up to 256 different combinations of up to 8 different conditions, in the most compact form.
Array accesses with statically predictable access patterns are a major source of data parallelism.
### Comparison with other data structures {#comparison_with_other_data_structures}
Dynamic arrays or growable arrays are similar to arrays but add the ability to insert and delete elements; adding and deleting at the end is particularly efficient. However, they reserve linear (Θ(*n*)) additional storage, whereas arrays do not reserve additional storage.
Associative arrays provide a mechanism for array-like functionality without huge storage overheads when the index values are sparse. For example, an array that contains values only at indexes 1 and 2 billion may benefit from using such a structure. Specialized associative arrays with integer keys include Patricia tries, Judy arrays, and van Emde Boas trees.
Balanced trees require O(log *n*) time for indexed access, but also permit inserting or deleting elements in O(log *n*) time, whereas growable arrays require linear (Θ(*n*)) time to insert or delete elements at an arbitrary position.
Linked lists allow constant time removal and insertion in the middle but take linear time for indexed access. Their memory use is typically worse than arrays, but is still linear.
An Iliffe vector is an alternative to a multidimensional array structure. It uses a one-dimensional array of references to arrays of one dimension less. For two dimensions, in particular, this alternative structure would be a vector of pointers to vectors, one for each row(pointer on c or c++). Thus an element in row *i* and column *j* of an array *A* would be accessed by double indexing (*A*\[*i*\]\[*j*\] in typical notation). This alternative structure allows jagged arrays, where each row may have a different size---or, in general, where the valid range of each index depends on the values of all preceding indices. It also saves one multiplication (by the column address increment) replacing it by a bit shift (to index the vector of row pointers) and one extra memory access (fetching the row address), which may be worthwhile in some architectures.
| 623 |
Array (data structure)
| 3 |
2,052 |
# Array (data structure)
## Dimension
The *dimension* of an array is the number of indices needed to select an element. Thus, if the array is seen as a function on a set of possible index combinations, it is the dimension of the space of which its domain is a discrete subset. Thus a one-dimensional array is a list of data, a two-dimensional array is a rectangle of data, a three-dimensional array a block of data, etc.
This should not be confused with the dimension of the set of all matrices with a given domain, that is, the number of elements in the array. For example, an array with 5 rows and 4 columns is two-dimensional, but such matrices form a 20-dimensional space. Similarly, a three-dimensional vector can be represented by a one-dimensional array of size three
| 137 |
Array (data structure)
| 4 |
2,063 |
# Aristide Maillol
**Aristide Joseph Bonaventure Maillol** (`{{IPA|fr|mɑjɔl|lang}}`{=mediawiki}; December 8, 1861 -- September 27, 1944) was a French sculptor, painter, and printmaker.
He began his career as a painter and developed an early interest in the decorative arts. He became primarily interested in sculpture from his early 40s. Maillol was one of the most famous sculptors of his time. His work inspired artists such as Picasso, Henri Matisse and Henry Moore.
## Biography
Maillol was born in Banyuls-sur-Mer, Roussillon. He decided at an early age to become a painter, and moved to Paris in 1881 to study art. After several applications and several years of living in poverty, his enrollment in the École des Beaux-Arts was accepted in 1885, and he studied there under Jean-Léon Gérôme and Alexandre Cabanel. His early paintings show the influence of his contemporaries Pierre Puvis de Chavannes and Paul Gauguin.
Gauguin encouraged his growing interest in decorative art, an interest that led Maillol to take up tapestry design. In 1893 Maillol opened a tapestry workshop in Banyuls, producing works whose high technical and aesthetic quality gained him recognition for renewing this art form in France. He began making small terracotta sculptures in 1895, and within a few years his concentration on sculpture led to the abandonment of his work in tapestry. In July 1896, Maillol married Clotilde Narcis, one of his employees at his tapestry workshop. Their only son, Lucian, was born that October.
Maillol\'s first major sculpture, *A Seated Woman*, was modeled after his wife. The first version (in the Museum of Modern Art, New York) was completed in 1902, and renamed *La Méditerranée*. Maillol, believing that \"art does not lie in the copying of nature\", produced a second, less naturalistic version in 1905. In 1902, the art dealer Ambroise Vollard provided Maillol with his first exhibition.
The subject of nearly all of Maillol\'s mature work is the female body, treated with a classical emphasis on stable forms. The figurative style of his large bronzes is perceived as an important precursor to the greater simplifications of Henry Moore, and his serene classicism set a standard for European (and American) figure sculpture until the end of World War II.
Josep Pla said of Maillol, \"These archaic ideas, Greek, were the great novelty Maillol brought into the tendency of modern sculpture. What you need to love from the ancients is not the antiquity, it is the sense of permanent, renewed novelty, that is due to the nature and reason.\"
His important public commissions include a 1912 commission for a monument to Cézanne, as well as numerous war memorials commissioned after World War I.
Maillol served as a juror with Florence Meyer Blumenthal in awarding the Prix Blumenthal (1919--1954) a grant awarded to painters, sculptors, decorators, engravers, writers, and musicians.
He made a series of woodcut illustrations for an edition of Vergil\'s *Eclogues* published by Harry Graf Kessler in 1926--27. He also illustrated *Daphnis and Chloe* by Longus (1937) and *Chansons pour elle* by Paul Verlaine (1939).
He died in Banyuls at the age of eighty-two, in an automobile accident. While driving home during a thunderstorm, the car in which he was a passenger skidded off the road and rolled over. A large collection of Maillol\'s work is maintained at the Musée Maillol in Paris, which was established by Dina Vierny, Maillol\'s model and platonic companion during the last 10 years of his life. His home a few kilometers outside Banyuls, also the site of his final resting place, has been turned into a museum, the Musée Maillol Banyuls-sur-Mer, where a number of his works and sketches are displayed.
Three of his bronzes grace the grand staircase of the Metropolitan Opera House in New York City: *Summer* (1910--11), *Venus Without Arms* (1920), and*Kneeling Woman: Monument to Debussy* (1950--55). The third, the artist\'s only reference to music, is a copy of an original created for the French city of Saint-Germain-en-Laye, Claude Debussy\'s birthplace.
## Nazi-looted art {#nazi_looted_art}
During the German occupation of France, dozens of artworks by Maillol were seized by the Nazi looting organization known as the E.R.R. or Reichsleiter Rosenberg Taskforce. The Database of Art Objects at the Jeu de Paume lists thirty artworks by Maillol. The German Lost Art Foundation database lists 33 entries for Maillol. The German Historical Museum\'s database for artworks recovered by the Allies at the Munich Central Collecting Point has 13 items related to Maillol. Maillol\'s sculpture \"Head of Flora\" was found in the stash of Cornelius Gurlitt, son of Hitler\'s art dealer Hildebrand Gurlitt together with lithographs, drawings and paintings.
A photograph from May 24, 1946, shows \"Six men, members of the Monuments, Fine Arts & Archives section of the military, prepare Aristide Maillol\'s sculpture *Baigneuse à la draperie*, looted during World War II for transport to France. Sculpture is labeled with sign: Wiesbaden, no. 31.\"
Jewish art collectors whose artworks by Maillol were looted by Nazis include Hugo Simon, Alfred Flechtheim and many others.
| 825 |
Aristide Maillol
| 0 |
2,063 |
# Aristide Maillol
## Works
- Mme Henry Clemens van de Velde (c. 1899)
- *The Mediterranean (1902--05)*
- *Action in Chains* (1905)
- *Flora, Nude* (1910)
- *L\'Été sans bras* (1911)
- *Bathing Woman with Raised Arms* (1921)
- *Nymph* (1930)
- *The Mountain* (1937)
- *L\'Air* (1938)
- *The River* (1938--43)
- *Harmonie* (1944)
- *Femme à l'Echarpe* (circa 1919--20, cast in bronze in edition of 6; certificate of authenticity from model Dina Vierny dated 29.10.1970)
## Legacy and Contemporary Influence {#legacy_and_contemporary_influence}
Aristide Maillol\'s work has had a profound and enduring impact on both modern and contemporary art, particularly within the realms of sculpture, the representation of the human body, and the revival of classical forms in the 20th century. His restrained, monumental approach to the female figure influenced numerous artists, sparking discussions about form, abstraction, and the essence of sculpture itself.
One of Maillol\'s most significant contributions was his rejection of the exaggerated dynamism that characterized much of late 19th-century sculpture, notably the work of his contemporary, Auguste Rodin. Maillol\'s figures, with their serene and stable forms, marked a return to classical simplicity and purity. This approach resonated with artists like Henry Moore, who cited Maillol as an early influence on his own move toward abstraction and monumentality. Moore admired the way Maillol\'s work avoided excessive detail, allowing the essential form of the human body to take precedence. In his 1941 writings, Moore stated, \"Maillol\'s influence was important to me because of the calm and permanence that his figures suggest, as well as his return to classical balance and volume.\" \</ref\>
Additionally, Hans Arp, a Dadaist and Surrealist artist, found inspiration in Maillol\'s organic forms, which he believed offered a \"timeless universality.\" Arp\'s abstracted, rounded sculptures share a kinship with Maillol\'s pursuit of essential, elemental forms, though Arp pushed these ideas further into abstraction.
Art historians such as Hilton Kramer and Albert Elsen have extensively discussed Maillol\'s unique place in modern sculpture. Kramer remarked that Maillol\'s works possess an \"elemental calm\" and reflect an anti-Romantic sentiment, contrasting sharply with the emotional intensity of Rodin. Elsen, in his study of Maillol\'s work, argued that his influence can be seen in the development of modernist sculpture, particularly through his focus on the essential harmony of form and space, a concept that paved the way for mid-century minimalism.
In more recent decades, Maillol\'s sculptures have continued to inspire contemporary artists exploring themes of memory, identity, and the body. The French-Lebanese contemporary artist Oliver Aoun incorporated Maillol\'s sculptures into his project *Lisa Rediviva* (2012), which juxtaposes classical representations of the female form with fragmented images of the Mona Lisa. Aoun\'s work engaged with the legacy of Western iconography, questioning the colonial and patriarchal structures embedded within these revered forms. In reinterpreting Maillol\'s figures, Oliver Aoun critiqued the traditional Western gaze and proposed a more inclusive dialogue around the representation of women in art.
Furthermore, exhibitions such as the 2011 show at the Musée Maillol in Paris, which focused on the dialogue between Maillol and contemporary sculptors, underscore the relevance of his oeuvre in ongoing conversations about the body, space, and abstraction. Artists such as Jean-Michel Othoniel and Louise Bourgeois have also been said to engage with the themes of solidity and fluidity in ways that echo Maillol\'s approach to form.
Maillol\'s influence persists not only in sculpture but also in broader conversations about the role of classical ideals in contemporary art, inviting ongoing re-evaluation and reinterpretation
| 575 |
Aristide Maillol
| 1 |
2,064 |
# Antonio Canova
**Antonio Canova** (`{{IPA|it|anˈtɔːnjo kaˈnɔːva}}`{=mediawiki}; 1 November 1757 -- 13 October 1822) was an Italian Neoclassical sculptor, famous for his marble sculptures. Often regarded as the greatest of the Neoclassical artists, his sculpture was inspired by the Baroque and the classical revival, and has been characterised as having avoided the melodramatics of the former, and the cold artificiality of the latter.
## Life
### Possagno
In 1757, Antonio Canova was born in the Venetian Republic city of Possagno to Pietro Canova, a stonecutter, and Angela Zardo Fantolin. In 1761, his father died. A year later, his mother remarried. In 1762, he was put into the care of his paternal grandfather Pasino Canova, who was a stonemason, owner of a quarry, and was a \"sculptor who specialized in altars with statues and low reliefs in late Baroque style\". He led Antonio into the art of sculpting.
Before the age of ten, Canova began making models in clay, and carving marble. Indeed, at the age of nine, he executed two small shrines of Carrara marble that are still extant. After these works, he appears to have been constantly employed under his grandfather.
### Venice
In 1770, he was an apprentice for two years to Giuseppe Bernardi, who was also known as \'Torretto\'. Afterwards, he was under the tutelage of Giovanni Ferrari until he began his studies at the Accademia di Belle Arti di Venezia. At the academy, he won several prizes. During this time, he was given his first workshop within a monastery by some local monks.
The Senator Giovanni Falier commissioned Canova to produce statues of Orpheus and Eurydice for his garden -- the Villa Falier at Asolo. The statues were begun in 1775, and both were completed by 1777. The pieces exemplify the late Rococo style. On the year of their completion, both works were exhibited for the Feast of the Ascension in Piazza San Marco. Widely praised, the works won Canova his first renown among the Venetian elite. Another Venetian who is said to have commissioned early works from Canova was the abate Filippo Farsetti, whose collection at Ca\' Farsetti on the Grand Canal he frequented.
In 1779, Canova opened his own studio at Calle Del Traghetto at S. Maurizio. At this time, Procurator Pietro Vettor Pisani commissioned Canova\'s first marble statue: a depiction of Daedalus and Icarus. The statue inspired great admiration for his work at the annual art fair; Canova was paid 100 gold zecchini for the completed work. At the base of the statue, Daedalus\' tools are scattered about; these tools are also an allusion to Sculpture, of which the statue is a personification. With such an intention, there is suggestion that Daedalus is a portrait of Canova\'s grandfather Pasino.
| 456 |
Antonio Canova
| 0 |
2,064 |
# Antonio Canova
## Life
### Rome
Canova arrived in Rome, on 28 December 1780. Prior to his departure, his friends had applied to the Venetian Senate for a pension. Successful in the application, the stipend allotted amounted to three hundred ducats, limited to three years.
While in Rome, Canova spent time studying and sketching the works of Michelangelo.
In 1781, Girolamo Zulian -- the Venetian ambassador to Rome -- hired Canova to sculpt *Theseus and the Minotaur*. Zulian played a fundamental role in Canova\'s rise to fame, turning some rooms of his palace into a studio for the artist and placing his trust in him despite Canova\'s early critics in Rome. The statue depicts the victorious Theseus seated on the lifeless body of a Minotaur. The initial spectators were certain that the work was a copy of a Greek original, and were shocked to learn it was a contemporary work. The highly regarded work is now in the collection of the Victoria & Albert Museum, in London.
Between 1783 and 1785, Canova arranged, composed, and designed a funerary monument dedicated to Clement XIV for the Church of Santi Apostoli. After another two years, the work met completion in 1787. The monument secured Canova\'s reputation as the pre-eminent living artist.
In 1792, he completed another cenotaph, this time commemorating Clement XIII for St. Peter\'s Basilica. Canova harmonized its design with the older Baroque funerary monuments in the basilica.
In 1790, he began to work on a funerary monument for Titian, which was eventually abandoned by 1795. During the same year, he increased his activity as a painter. Canova was notoriously disinclined to restore sculptures. However, in 1794 he made an exception for his friend and early patron Zulian, restoring a few sculptures that Zulian had moved from Rome to Venice.
The following decade was extremely productive, beginning works such as *Hercules and Lichas*, *Cupid and Psyche*, *Hebe*, *Tomb of Duchess Maria Christina of Saxony-Teschen*, and *The Penitent Magdalene*.
In 1797, he went to Vienna, but only a year later, in 1798, he returned to Possagno for a year.`{{NoteTag|''The Glory of Venice: Art in the Eighteenth Century'' states (p. 441) that Canova left Venice when it fell, tried to escape to America and then went to Possagno. The fall of Venice was in 1797. There appears to be some gap in knowledge that would correct or amend these accounts. The first reference to Vienna is an online source, the second is the ''Encyclopædia Britannica, 1911'' which has already proven itself incorrect in some areas. ''The Glory of Venice'' has proven itself more accurate, but it is undated, leaving speculation of time frame.}}`{=mediawiki}
| 441 |
Antonio Canova
| 1 |
2,064 |
# Antonio Canova
## Life
### France and England {#france_and_england}
By 1800, Canova was the most celebrated artist in Europe. He systematically promoted his reputation by publishing engravings of his works and having marble versions of plaster casts made in his workshop. He became so successful that he had acquired patrons from across Europe including France, England, Russia, Austria and Holland, as well as several members from different royal lineages, and prominent individuals. Among his patrons were Napoleon and his family, for whom Canova produced much work, including several depictions between 1803 and 1809. The most notable representations were that of *Napoleon as Mars the Peacemaker*, and *Venus Victrix* which was portrayal of Pauline Bonaparte.
*Napoleon as Mars the Peacemaker* had its inception after Canova was hired to make a bust of Napoleon in 1802. The statue was begun in 1803, with Napoleon requesting to be shown in a French General\'s uniform, Canova rejected this, insisting on an allusion to Mars, the Roman god of War. It was completed in 1806. In 1811, the statue arrived in Paris, but not installed; neither was its bronze copy in the Foro Napoleonico in Milan. In 1815, the original went to the Duke of Wellington, after his victory at Waterloo against Napoleon.
*Venus Victrix* was originally conceived as a robed and recumbent sculpture of Pauline Borghese in the guise of Diana. Instead, Pauline ordered Canova to make the statue a nude Venus. The work was not intended for public viewing.
Other works for the Napoleon family include, a bust of Napoleon, a statue of Napoleon\'s mother, and Marie Louise as Concordia.
In 1802, Canova was assigned the post of \'Inspector-General of Antiquities and Fine Art of the Papal State\', a position formerly held by Raphael. One of his activities in this capacity was to pioneer the restoration of the Appian Way by restoring the tomb of Servilius Quartus. In 1808 Canova became an associated member of the Royal Institute of Sciences, Literature and Fine Arts of the Kingdom of Holland.
In 1814, he began his *The Three Graces*.
In 1815, he was named \'Minister Plenipotentiary of the Pope,\' and was tasked by Pope Pius VI with recovering various works of art that were taken to Paris by Napoleon under the terms of the Treaty of Paris (1815). At the Louvre, he faced resistance to restitution from Director Vivant Denon and, due to the works\' large size or unclear location, was forced to leave behind major pieces, such as Paolo Veronese\'s painting *The Wedding at Cana.*
Also in 1815, he visited London, and met with Benjamin Haydon. It was after the advice of Canova that the Elgin Marbles were acquired by the British Museum, with plaster copies sent to Florence, according to Canova\'s request.
| 460 |
Antonio Canova
| 2 |
2,064 |
# Antonio Canova
## Life
### Returning to Italy {#returning_to_italy}
In 1816, Canova returned to Rome with some of the art Napoleon had taken. He was rewarded with several marks of distinction: he was appointed President of the Accademia di San Luca, inscribed into the \"Golden Book of Roman Nobles\" by the Pope\'s own hands, and given the title of Marquis of Ischia, alongside an annual pension of 3,000 crowns.
In 1819, he commenced and completed his commissioned work *Venus Italica* as a replacement for the Venus de\' Medici.
After his 1814 proposal to build a personified statue of Religion for St. Peter\'s Basilica was rejected, Canova sought to build his own temple to house it. This project came to be the Tempio Canoviano. Canova designed, financed, and partly built the structure himself. The structure was to be a testament to Canova\'s piety. The building\'s design was inspired by combining the Parthenon and the Pantheon together. On 11 July 1819, Canova laid the foundation stone dressed in red Papal uniform and decorated with all his medals. It first opened in 1830, and was finally completed in 1836. After the foundation-stone of this edifice had been laid, Canova returned to Rome; but every succeeding autumn he continued to visit Possagno to direct the workmen and encourage them with rewards.
During the period that intervened between commencing operations at Possagno and his death, he executed or finished some of his most striking works. Among these were the group *Mars and Venus*, the colossal figure of Pius VI, the Pietà, the *St John*, and a colossal bust of his friend, the Count Leopoldo Cicognara.
In 1820, he made a statue of George Washington for the state of North Carolina. As recommended by Thomas Jefferson, the sculptor used the marble bust of Washington by Giuseppe Ceracchi as a model. It was delivered on 24 December 1821. The statue and the North Carolina State House where it was displayed were later destroyed by fire in 1831. A plaster replica was sent by King Victor Emmanuel III of Italy in 1910, now on view at the North Carolina Museum of History. A marble copy was sculpted by Romano Vio in 1970, now on view in the rotunda of the capitol building.
In 1822, he journeyed to Naples, to superintend the construction of wax moulds for an equestrian statue of Ferdinand VII. The adventure was disastrous to his health, but soon became healthy enough to return to Rome. From there, he voyaged to Venice; however, on 13 October 1822, he died there at the age of 64. As he never married, the name became extinct, except through his stepbrothers\' lineage of Satori-Canova.
On 12 October 1822, Canova instructed his brother to use his entire estate to complete the Tempio in Possagno.
On 25 October 1822, his body was placed in the Tempio Canoviano. His heart was interred at the Basilica di Santa Maria Gloriosa dei Frari in Venice, and his right hand preserved in a vase at the Accademia di Belle Arti di Venezia.
His memorial service was so grand that it rivaled the ceremony that the city of Florence held for Michelangelo in 1564.
In 1826, Giovanni Battista Sartori sold Canova\'s Roman studio and took every plaster model and sculpture to Possagno, where they were installed in the gypsotheque of the Tempio Canoviano.
thumb\|Commemorative plaque at the place of life and death of Antonio Canova, in *Rio Orseolo o del Corval*
| 575 |
Antonio Canova
| 3 |
2,064 |
# Antonio Canova
## Works
Among Canova\'s most notable works are:
### *Psyche Revived by Cupid\'s Kiss* (1787) {#psyche_revived_by_cupids_kiss_1787}
*Main article: Psyche Revived by Cupid\'s Kiss*
*Psyche Revived by Cupid\'s Kiss* was commissioned in 1787 by Colonel John Campbell. It is regarded as a masterpiece of Neoclassical sculpture, but shows the mythological lovers at a moment of great emotion, characteristic of the emerging movement of Romanticism. It represents the god Cupid in the height of love and tenderness, immediately after awakening the lifeless Psyche with a kiss.
### *Napoleon as Mars the Peacemaker* (1802--1806) {#napoleon_as_mars_the_peacemaker_18021806}
*Napoleon as Mars the Peacemaker* had its inception after Canova was hired to make a bust of Napoleon in 1802. The statue was begun in 1802, with Napoleon requesting to be shown in a French General\'s uniform, Canova rejected this, insisting on an allusion to Mars, the Roman god of War. It was completed in 1806. In 1811, the statue arrived in Paris, but not installed; neither was its bronze copy in the Foro Napoleonico in Milan. In 1815, the original went to the Duke of Wellington, after his victory at Waterloo against Napoleon and is on display at Apsley House.
### *Perseus Triumphant* (1804--1806) {#perseus_triumphant_18041806}
*Perseus Triumphant*, sometimes called *Perseus with the Head of Medusa*, was a statue commissioned by tribune Onorato Duveyriez. It depicts the Greek hero Perseus after his victory over the Gorgon Medusa.
The statue was based freely on the Apollo Belvedere and the Medusa Rondanini.
Napoleon, after his 1796 Italian Campaign, took the Apollo Belvedere to Paris. In the statue\'s absence, Pope Pius VII acquired Canova\'s *Perseus Triumphant* and placed the work upon the *Apollo*\'s pedestal. The statue was so successful that when the *Apollo* was returned, *Perseus* remained as a companion piece.
One replica of the statue was commissioned from Canova by the Polish countess Waleria Tarnowska; it\'s now displayed in the Metropolitan Museum of Art in New York City.
Karl Ludwig Fernow said of the statue that \"every eye must rest with pleasure on the beautiful surface, even when the mind finds its hopes of high and pure enjoyment disappointed.\"
### *Venus Victrix* (1805--1808) {#venus_victrix_18051808}
*Venus Victrix* ranks among the most famous of Canova\'s works. Originally, Canova wished the depiction to be of a robed Diana, but Pauline Borghese insisted to appear as a nude Venus. The work was not intended for public viewing.
### *The Three Graces* (1814--1817) {#the_three_graces_18141817}
*Main article: The Three Graces (Canova)*
John Russell, the 6th Duke of Bedford, commissioned a version of the now famous work. He had previously visited Canova in his studio in Rome in 1814 and had been immensely impressed by a carving of the Graces the sculptor had made for the Empress Joséphine. When the Empress died in May of the same year he immediately offered to purchase the completed piece, but was unsuccessful as Josephine\'s son Eugène de Beauharnais claimed it (his son Maximilian, Duke of Leuchtenberg brought it to St. Petersburg, where it can now be found in the Hermitage Museum). Undeterred, the Duke commissioned another version for himself.
The sculpting process began in 1814 and was completed in 1817. Finally in 1819 it was installed at the Duke\'s residence in Woburn Abbey. Canova even made the trip over to England to supervise its installation, choosing for it to be displayed on a pedestal adapted from a marble plinth with a rotating top. This version is now owned jointly by the Victoria and Albert Museum and the National Galleries of Scotland, and is alternately displayed at each.
| 590 |
Antonio Canova
| 4 |
2,064 |
# Antonio Canova
## Artistic process {#artistic_process}
Canova had a distinct, signature style in which he combined Greek and Roman art practices with early stirrings of romanticism to delve into a new path of Neoclassicism. Canova\'s sculptures fall into three categories: Heroic compositions, compositions of grace, and sepulchral monuments. In each of these, Canova\'s underlying artistic motivations were to challenge, if not compete, with classical statues.
Canova refused to take in pupils and students, but would hire workers to carve the initial figure from the marble. According to art historian Giuseppe Pavanello, \"Canova\'s system of work concentrated on the initial idea, and on the final carving of the marble\". He had an elaborate system of comparative pointing so that the workers were able to reproduce the plaster form in the selected block of marble. These workers would leave a thin veil over the entire statue so Canova\'s could focus on the surface of the statue.
While he worked, he had people read to him select literary and historical texts.
### Last touch {#last_touch}
During the last quarter of the eighteenth century, it became fashionable to view art galleries at night by torchlight. Canova was an artist that leapt on the fad and displayed his works of art in his studio by candlelight. As such, Canova would begin to finalize the statue with special tools by candlelight, to soften the transitions between the various parts of the nude. After a little recarving, he began to rub the statue down with pumice stone, sometimes for periods longer than weeks or months. If that was not enough, he would use tripoli (rottenstone) and lead.
He then applied a now unknown chemical-composition of patina onto the flesh of the figure to lighten the skin tone. Importantly, his friends also denied any usage of acids in his process.
## Criticisms
Conversations revolving around the justification of art as superfluous usually invoked the name of Canova. Karl Ludwig Fernow believed that Canova was not Kantian enough in his aesthetic, because emphasis seemed to have been placed on agreeableness rather than Beauty. Canova was faulted for creating works that were artificial in complexity.
## Legacy
Although the Romantic period artists buried Canova\'s name soon after he died, he is slowly being rediscovered. Giuseppe Pavanello wrote in 1996 that \"the importance and value of Canova\'s art is now recognized as holding in balance the last echo of the Ancients and the first symptom of the restless experimentation of the modern age\".
Canova spent large parts of his fortune helping young students and sending patrons to struggling sculptors, including Sir Richard Westmacott and John Gibson.
He was introduced into various orders of chivalry.
A number of his works, sketches, and writings are collected in the *Sala Canoviana* of the Museo Civico of Bassano del Grappa. Other works, including plaster casts are the Museo Canoviano in Asolo.
In 2018, a crater on Mercury was named in his honor.
## Literary inspirations {#literary_inspirations}
Two of Canova\'s works appear as engravings in *Fisher\'s Drawing Room Scrap Book*, 1834, with poetical illustrations by Letitia Elizabeth Landon. These are of *The Dancing Girl* and *Hebe*.
### Commemorations
- Canova, South Dakota
- Via Antonio Canova, in Treviso
- Aeroporto di Treviso A. Canova
- The Museo Canova in Possagno
- Tempio Canoviano, in Possagno
| 550 |
Antonio Canova
| 5 |
2,064 |
# Antonio Canova
## Gallery
Antonio Canova from the studio if Canova c.1813.jpg\|Antonio Canova from the studio of Canova, c. 1813 Amor-Psyche-Canova-JBU02.JPG\|*Psyche Revived by Cupid\'s Kiss*, 1787--1793, Louvre Amor-Psyche-Canova-JBU04.JPG\|*Psyche Revived by Cupid\'s Kiss*, 1787--1793, Louvre (detail) Venus Italica by Canova.jpg\|Antonio Canova, Detail of *Venus Italica*, 1804--1812, Galleria Palatina, Florence Antonio Canova Teseo defeats the centaur.jpg\|*Theseus Fighting the Centaur* (1804--1819), Kunsthistorisches Museum, Vienna`{{NoteTag|Napoleon ordered it for the Corso in Milan; Emperor Franz I bought it for the Theseus Temple in the Volksgarten in Vienna; moved to Kunsthistorisches Museum in 1891.}}`{=mediawiki} Antonio canova, danzatrice, ermitage, 01.JPG\|*Dancer*, 1811--1812, The State Hermitage Museum Canova-Three Graces 0 degree view.jpg\|*The Three Graces*, 1814--1817, Hermitage Venus Italica MET DP108444.jpg\|*Venus Italica*, c. 1822--23, Metropolitan Museum of Art Terpsichore by Antonio Canova.jpg\|*Terpsichore Lyran* (Muse of Lyric Poetry) Perseus Canova Pio-Clementino Inv969.jpg\|*Perseus Triumphant*, Vatican Canova, maddalena penitente, 02.JPG\|*The Penitent Magdalene*, Palazzo Doria-Tursi, Genoa Napoleon-Canova-London JBU01.jpg\|*Napoleon as Mars the Peacemaker*, Apsley House, London Paolina Borghese (Canova).jpg\|Pauline Bonaparte as *Venus Victrix*, now at the Galleria Borghese Florence, Santa Croce, Antonio Canova, tomb of Vittorio Alfieri, 1810.jpg\|Monumental tomb of Vittorio Alfieri, Santa Croce, Florence, 1810 Tomb Monument of Pius VI Gregorovius.jpg\|Monument to Pius VI Tomb of Pope Clement XIII Gregorovius.jpg\|Tomb of Clement XIII Tomb of Pope Clement XIV Gregorovius.jpg\|Tomb of Pope Clement XIV Frith, Francis (1822-1898) - n. 2340 - Tomb of Marie Christine by Canova - Vienna.jpg\|Cenotaph to Maria Christina of Austria in the Augustinerkirche Antonio Canova Cenotaph of Archduchess Maria Christina Augustinerkirche (Wien) panoramic sculpture Austria 2014 photo Paolo Villa August FOTO8412 - FOTO8425auto.jpg\|Panorama of Cenotaph to Maria Christina of Austria Basilica di Santa Maria dei Frari interno - Monumento di Canova.jpg\|Monument to Canova in the Basilica di Santa Maria Gloriosa dei Frari, designed by Canova as a mausoleum for the painter Titian Italy, Antonio Canova Medal by Putinati.jpg\|Antonio Canova medal by Putinati (Venice) Maschera funebre di Antonio Canova - Gesso - Museo Correr
| 313 |
Antonio Canova
| 6 |
2,070 |
# Act of Settlement 1701
The **Act of Settlement** (12 & 13 Will. 3. c. 2) is an act of the Parliament of England that settled the succession to the English and Irish crowns to only Protestants, which passed in 1701. More specifically, anyone who became a Roman Catholic, or who married one, became disqualified to inherit the throne. This had the effect of deposing the remaining descendants of Charles I, other than his Protestant granddaughter Anne, as the next Protestant in line to the throne was Sophia of Hanover. Born into the House of Wittelsbach, she was a granddaughter of James VI and I from his most junior surviving line, with the crowns descending only to her non-Catholic heirs. Sophia died less than two months before Queen Anne, and Sophia\'s son succeeded to the throne as King George I, starting the Hanoverian dynasty in Britain.
The Act of Supremacy 1558 (1 Eliz. 1. c. 1) had confirmed the independence of the Church of England from Roman Catholicism under the English monarch. One of the principal factors which contributed to the Glorious Revolution was the perceived assaults made on the Church of England by King James II, a Roman Catholic, who was deposed in favour of his Protestant daughter Mary II and her husband William III. The need for this Act of Settlement was prompted by the inability of William and Mary, as well as of Mary\'s Protestant sister (the future Queen Anne), to produce any surviving children, and by the perceived threat posed by the pretensions to the throne by remaining Roman Catholic members of the House of Stuart.
The act played a key role in the formation of the Kingdom of Great Britain as, though England and Scotland had shared a monarch since 1603, they had remained separately governed countries, with the Act catalysing the Union of England and Scotland. However, the Parliament of Scotland was more reluctant to abandon the House of Stuart, members of which had been Scottish monarchs long before they became English. Moreover, the Act also placed limits on both the role of foreigners in the British government and the power of the monarch with respect to the Parliament of England, though some of those provisions have been altered by subsequent legislation.
Along with the Bill of Rights 1689, the Act of Settlement remains today one of the main constitutional laws governing the succession not only to the throne of the United Kingdom, but to those of the other Commonwealth realms, whether by assumption or by patriation. The Act of Settlement cannot be altered in any realm except by that realm\'s own parliament and, by convention, only with the consent of all the other realms, as it touches on the succession to the shared crown. On 26 March 2015, following the Perth Agreement, legislation amending the Act came into effect across the Commonwealth realms that removed the disqualification arising from marriage to a Roman Catholic and instituted absolute primogeniture.
| 495 |
Act of Settlement 1701
| 0 |
2,070 |
# Act of Settlement 1701
## Background
Following the Glorious Revolution, the line of succession to the English throne was governed by the Bill of Rights 1689, which declared that the flight of James II from England to France during the revolution amounted to an abdication of the throne and that James\'s daughter Mary II and her husband/cousin, William III (William of Orange, who was also James\'s nephew), were James\'s successors. The Bill of Rights also provided that the line of succession would go through Mary\'s Protestant descendants by William and any possible future husband should she outlive him, then through Mary\'s sister Anne and her Protestant descendants, and then to the Protestant descendants of William III by a possible later marriage should he outlive Mary. During the debate, the House of Lords had attempted to append Sophia and her descendants to the line of succession, but the amendment failed in the Commons.
Mary II died childless in 1694, after which William III did not remarry. In 1700, Prince William, Duke of Gloucester, who was Anne\'s only child to survive infancy, died of what may have been smallpox at the age of 11. Thus, Anne was left as the only person in line to the throne. The Bill of Rights excluded Catholics from the throne, which ruled out James II and his children (as well as their descendants) sired after he converted to Catholicism in 1668. However, it did not provide for the further succession after Anne. Parliament thus saw the need to settle the succession on Sophia and her descendants, and thereby guarantee the continuity of the Crown in the Protestant line.
With religion and lineage initially decided, the ascendancy of William of Orange in 1689 would also bring his partiality to his Dutch favourites that followed. By 1701, anti-Dutch sentiment was widespread in England and action was considered necessary.
| 311 |
Act of Settlement 1701
| 1 |
2,070 |
# Act of Settlement 1701
## The act {#the_act}
The Act of Settlement provided that the throne would pass to the Electress Sophia of Hanover -- a granddaughter of James VI and I and a niece of King Charles I -- and her descendants, but it excluded \"for ever\" \"all and every Person and Persons who \... is are or shall be reconciled to or shall hold Communion with the See or Church of Rome or shall profess the Popish Religion or shall marry a Papist\". Thus, those who were Roman Catholics, and those who married Roman Catholics, were barred from ascending the throne.
### Conditional provisions {#conditional_provisions}
The act contained eight additional provisions that were to only come into effect upon the death of both William and Anne:
Firstly, the monarch \"shall join in communion with the Church of England\". This was intended to ensure the exclusion of a Roman Catholic monarch. Along with James II\'s perceived despotism, his religion was the main cause of the Glorious Revolution, and of the previous linked religious and succession problems which had been resolved by the joint monarchy of William III and Mary II.
Second, if a person not native to England comes to the throne, England will not wage war for \"any dominions or territories which do not belong to the Crown of England, without the consent of Parliament\". This would become relevant when a member of the House of Hanover ascended the British throne, as he would retain the territories of the Electorate of Hanover in what is now Lower Saxony (Germany), then part of the Holy Roman Empire. This provision has been dormant since Queen Victoria ascended the throne, because she did not inherit Hanover under the Salic Laws of the German-speaking states.
Third, no monarch may leave \"the dominions of England, Scotland, or Ireland\", without the consent of Parliament. This provision was repealed in 1716, at the request of George I who was also the Elector of Hanover and Duke of Brunswick-Lüneburg within the Holy Roman Empire; because of this, and also for personal reasons, he wished to visit Hanover from time to time.
Fourth, all government matters within the jurisdiction of the Privy Council were to be transacted there, and all council resolutions were to be signed by those who advised and consented to them. This was because Parliament wanted to know who was deciding policies, as sometimes councillors\' signatures normally attached to resolutions were absent. This provision was repealed early in Queen Anne\'s reign, as many councillors ceased to offer advice and some stopped attending meetings altogether.
Fifth, no foreigner (\"no Person born out of the Kingdoms of England Scotland or Ireland or the Dominions thereunto belonging\"), even if naturalised or made a denizen (unless born of English parents), can be a Privy Councillor or a member of either House of Parliament, or hold \"any Office or Place of Trust, either Civill `{{sic}}`{=mediawiki} or Military, or to `{{sic}}`{=mediawiki} have any Grant of Lands, Tenements or Hereditaments from the Crown, to himself or to any other or others in Trust for him\". Subsequent nationality laws (today primarily the British Nationality Act 1981) made naturalised citizens the equal of those native born, and excluded Commonwealth citizens from the definition of foreigners, and citizens of the Irish Republic from the definition of aliens, but otherwise this provision still applies. It has however been disapplied in particular cases by a number of other statutes.
Sixth, no person who has an office under the monarch, or receives a pension from the Crown, was to be a Member of Parliament. This provision was inserted to avoid unwelcome royal influence over the House of Commons. It remains in force, but with several exceptions; ministers of the Crown were exempted early on before Anne\'s death in order to continue some degree of royal patronage, but had to stand for a by-election to re-enter the House upon such appointment until 1926. As a side effect, this provision means that members of the Commons seeking to resign from parliament can get around the prohibition on resignation by obtaining a sinecure in the control of the Crown; while several offices have historically been used for this purpose, two are currently in use: appointments generally alternate between the stewardships of the Chiltern Hundreds and of the Manor of Northstead.
Seventh, judges\' commissions are valid *quamdiu se bene gesserint* (during good behaviour) and if they do not behave themselves, they can be removed only by both Houses of Parliament (or in other Commonwealth realms the one House of Parliament, depending on the legislature\'s structure). This provision was the result of various monarchs influencing judges\' decisions, and its purpose was to assure judicial independence. This patent was used prior to 1701 but did not prevent Charles I from removing Sir John Walter as Chief Baron of the Exchequer.
Eighth, that \"no Pardon under the Great Seal of England be pleadable to an Impeachment by the Commons in Parliament\". This meant in effect that no pardon by the monarch was to save someone from being impeached by the House of Commons.
### Family tree {#family_tree}
## Opposition
The Tory administration that replaced the Whig Junto in 1699 took responsibility for steering the Act through Parliament. As a result, it passed with little opposition, although five peers voted against it in the House of Lords, including the Earl of Huntingdon, his brother-in-law the Earl of Scarsdale and three others. While many shared their opposition to a \"foreign\" king, the general feeling was summed up as \"better a German prince than a French one\".
| 931 |
Act of Settlement 1701
| 2 |
2,070 |
# Act of Settlement 1701
## Legacy
For different reasons, various constitutionalists have praised the Act of Settlement: Henry Hallam called the Act \"the seal of our constitutional laws\" and David Lindsay Keir placed its importance above the Bill of Rights of 1689. Naamani Tarkow wrote: \"If one is to make sweeping statements, one may say that, save Magna Carta (more truly, its implications), the Act of Settlement is probably the most significant statute in English history\".
### Union of Scotland with England and Wales {#union_of_scotland_with_england_and_wales}
The Act of Settlement was, in many ways, the major cause of the union of Scotland with England and Wales to form the Kingdom of Great Britain. The Parliament of Scotland had not been consulted about the Act of Settlement, and, in response, passed the Act of Security 1704, through which Scotland reserved the right to choose its own successor to Queen Anne. Stemming from this, the Parliament of England decided that, to ensure the stability and future prosperity of Great Britain, full union of the two parliaments and nations was essential before Anne\'s death.
It used a combination of exclusionary legislation (the Alien Act 1705), politics, and bribery to achieve this within three years under the Act of Union 1707. This success was in marked contrast to the four attempts at political union between 1606 and 1689, which all failed owing to a lack of political will in both kingdoms. By virtue of Article II of the Treaty of Union, which defined the succession to the throne of Great Britain, the Act of Settlement became part of Scots law as well.
### Succession to the Crown {#succession_to_the_crown}
In addition to excluding James II, who died a few months after the act received royal assent, and his Roman Catholic children, Prince James (*The Old Pretender*) and the Princess Royal, the Act also excluded the descendants of Princess Henrietta, the youngest sister of James II. Henrietta\'s only child with surviving issue was Anne, Queen of Sardinia, a Roman Catholic, from whom descend all Jacobite pretenders after 1807.
With the legitimate descendants of Charles I either childless (in the case of his two grand-daughters the late Queen Mary II and her successor Queen Anne) or Roman Catholic, Parliament\'s choice was limited to Sophia of Hanover, the Protestant daughter of the late Elizabeth of Bohemia, the only other child of King James I to have survived childhood. Elizabeth had borne nine children who reached adulthood, of whom Sophia was the youngest daughter. However in 1701 Sophia was the senior Protestant one, therefore with a legitimate claim to the English throne; Parliament passed over her Roman Catholic siblings, namely her sister Louise Hollandine of the Palatinate, and their descendants, who included Elizabeth Charlotte, Duchess of Orléans; Louis Otto, Prince of Salm, and his aunts; Anne Henriette, Princess of Condé, and Benedicta Henrietta, Duchess of Brunswick-Lüneburg.
### Removal from the succession due to Catholicism {#removal_from_the_succession_due_to_catholicism}
Since the act\'s passing the most senior living member of the royal family to have married a Roman Catholic, and thereby to have been removed from the line of succession, is Prince Michael of Kent, who married Baroness Marie-Christine von Reibnitz in 1978; he was fifteenth in the line of succession at the time. He was restored to the line of succession in 2015 when the Succession to the Crown Act 2013 came into force, and became 34th in line.
The next most senior living descendant of the Electress Sophia who had been ineligible to succeed on this ground is George Windsor, Earl of St Andrews, the elder son of Prince Edward, Duke of Kent, who married the Roman Catholic Sylvana Palma Tomaselli in 1988. His son, Lord Downpatrick, converted to Roman Catholicism in 2003 and is the most senior descendant of Sophia to be barred as a result of his religion. In 2008 his daughter, Lady Marina Windsor, also converted to Catholicism and was removed from the line of succession. More recently, Peter Phillips, the son of Anne, Princess Royal, and eleventh in line to the throne, married Autumn Kelly; Kelly had been brought up as a Roman Catholic, but she converted to Anglicanism prior to the wedding. Had she not done so, Phillips would have forfeited his place in the succession upon their marriage, only to have it restored in 2015.
Excluding those princesses who have married into Roman Catholic royal families, such as Marie of Edinburgh, Victoria Eugenie of Battenberg and Princess Beatrice of Edinburgh, one member of the Royal Family (that is, with the style of *Royal Highness*) has converted to Roman Catholicism since the passage of the Act: the Duchess of Kent, wife of Prince Edward, Duke of Kent, who converted on 14 January 1994, but her husband did not lose his place in the succession because she was an Anglican at the time of their marriage.
### Present status {#present_status}
As well as being part of the law of the United Kingdom, the Act of Settlement was received into the laws of all the countries and territories over which the British monarch reigned. It remains part of the laws of the 15 Commonwealth realms and the relevant jurisdictions within those realms. In accordance with established convention, the Statute of Westminster 1931 and later laws, the Act of Settlement (along with the other laws governing the succession of the Commonwealth realms) may only be changed with the agreement of all the realms (and, in some federal realms, the constituent members of those federations). The Succession to the Crown Act 2013 changed many provisions of this Act.
| 927 |
Act of Settlement 1701
| 3 |
2,070 |
# Act of Settlement 1701
## Amendment proposals {#amendment_proposals}
Challenges have been made against the Act of Settlement, especially its provisions regarding Roman Catholics and preference for males. However, changing the act is a complex process, since the act governs the shared succession of all the Commonwealth realms. The Statute of Westminster 1931 acknowledges by established convention that any changes to the rules of succession may be made only with the agreement of all of the states involved, with concurrent amendments to be made by each state\'s parliament or parliaments. Further, as the current monarch\'s eldest child and, in turn, his eldest child, are Anglican males, any change to the succession laws would have no immediate implications. Consequently, there was little public concern with the issues and debate had been confined largely to academic circles until the November 2010 announcement that Prince William was to marry. This raised the question of what would happen if he were to produce first a daughter and then a son.
*The Times* reported on 6 November 1995 that Prince Charles had said on that day to Tony Blair and Paddy Ashdown that \"Catholics should be able to ascend to the British throne\". Ashdown claimed the Prince said: \"I really can\'t think why we can\'t have Catholics on the throne\". In 1998, during debate on a Succession to the Crown Bill, Junior Home Office Minister Lord Williams of Mostyn informed the House of Lords that the Queen had \"no objection to the Government\'s view that in determining the line of succession to the throne, daughters and sons should be treated in the same way.\"
### Australia
In October 2011 the Australian federal government was reported to have reached an agreement with all of the states on potential changes to their laws in the wake of amendments to the Act of Settlement. The practice of the Australian states---for example, New South Wales and Victoria---has been, when legislating to repeal some imperial statutes so far as they still applied in Australia, to provide that imperial statutes concerning the royal succession remain in force.
The legal process required at the federal level remains, theoretically, unclear. The Australian constitution, as was noted during the crisis of 1936, contains no power for the federal parliament to legislate with respect to the monarchy. Everything thus turns upon the status and meaning of clause 2 in the Commonwealth of Australia Constitution Act 1900, which provides: \"The provisions of this Act referring to the Queen shall extend to Her Majesty\'s heirs and successors in the sovereignty of the United Kingdom.\"
Anne Twomey reviews three possible interpretations of the clause.
- First: it \"mandates that whoever is the sovereign of the United Kingdom is also, by virtue of this external fact, sovereign of Australia\"; accordingly, changes to British succession laws would have no effect on Australian law,`{{dubious|date=June 2021}}`{=mediawiki} but if the British amendment changed the sovereign, then the new sovereign of the United Kingdom would automatically become the new sovereign of Australia.
- Second, it is \"merely an interpretative provision\", operating to ensure that references to \"the Queen\" in the Constitution are references to whoever may at the time be the incumbent of the \"sovereignty of the United Kingdom\" as determined with regard to Australia, following the Australia Act 1986, by Australian law.
- Or, third, it incorporates the United Kingdom rules of succession into the Commonwealth of Australia Constitution Act, which itself can now be altered only by Australia, according to the Australia Act 1986; in that way, the British rules of succession have been patriated to Australia and, with regard to Australia, are subject to amendment or repeal solely by Australian law.
However, Twomey expresses confidence that, if the High Court of Australia were to be faced with the problems of covering clause 2, it would find some way to conclude that, with regard to Australia, the clause is subject solely to Australian law. Canadian scholar Richard Toporoski theorised in 1998 that \"if, let us say, an alteration were to be made in the United Kingdom to the Act of Settlement 1701, providing for the succession of the Crown\... \[i\]t is my opinion that the domestic constitutional law of Australia or Papua New Guinea, for example, would provide for the succession in those countries of the same person who became Sovereign of the United Kingdom.\"
In practice, when legislating for the Perth Agreement (see below), the Australian governments took the approach of the states requesting, and referring power to, the federal government to enact the legislation on behalf of the states (under paragraph 51(xxxviii) of the Australian Constitution) and the Commonwealth of Australia.
| 771 |
Act of Settlement 1701
| 4 |
2,070 |
# Act of Settlement 1701
## Amendment proposals {#amendment_proposals}
### Canada
In Canada, where the Act of Settlement (*Acte d\'établissement*) is now a part of Canadian constitutional law, Tony O\'Donohue, a Canadian civic politician, took issue with the provisions that exclude Roman Catholics from the throne, and which make the monarch of Canada the Supreme Governor of the Church of England, requiring him or her to be an Anglican. This, he claimed, discriminated against non-Anglicans, including Catholics, who are the largest faith group in Canada. In 2002, O\'Donohue launched a court action that argued the Act of Settlement violated the *Canadian Charter of Rights and Freedoms*, but, the case was dismissed by the court. It found that, as the Act of Settlement is part of the Canadian constitution, the Charter of Rights and Freedoms, as another part of the same constitution, does not have supremacy over it. Also, the court noted that, while Canada has the power to amend the line of succession to the Canadian throne, the Statute of Westminster stipulates that the agreement of the governments of the fifteen other Commonwealth realms that share the Crown would first have to be sought if Canada wished to continue its relationship with these countries. An appeal of the decision was dismissed on 16 March 2005. Some commentators state that, as a result of this, any single provincial legislature could hinder any attempts to change this Act, and by extension, to the line of succession for the shared crown of all 16 Commonwealth realms. Others contend that that is not the case, and changes to the succession instituted by an Act of the Parliament of Canada \"\[in accord\] with the convention of symmetry that preserves the personal unity of the British and Dominion Crowns\".
With the announcement in 2007 of the engagement of Peter Phillips to Autumn Kelly, a Roman Catholic and a Canadian, discussion about the Act of Settlement was revived. Norman Spector called in *The Globe and Mail* for Prime Minister Stephen Harper to address the issue of the Act\'s bar on Catholics, saying Phillips\' marriage to Kelly would be the first time the provisions of the Act would bear directly on Canada---Phillips would be barred from acceding to the Canadian throne because he married a Roman Catholic Canadian. (In fact, Lord St Andrews had already lost his place in the line of succession when he married the Roman Catholic Canadian Sylvana Palma Tomaselli in 1988. But St Andrews\' place in the line of succession was significantly lower than Phillips\'.) Criticism of the Act of Settlement due to the Phillips--Kelly marriage was muted when Autumn Kelly converted to Anglicanism shortly before her marriage, thus preserving her husband\'s place in the line of succession.
| 454 |
Act of Settlement 1701
| 5 |
2,070 |
# Act of Settlement 1701
## Amendment proposals {#amendment_proposals}
### United Kingdom {#united_kingdom}
From time to time there has been debate over repealing the clause that prevents Roman Catholics, or those who marry one, from ascending to the British throne. Proponents of repeal argue that the clause is a bigoted anachronism; Cardinal Winning, who was leader of the Roman Catholic Church in Scotland, called the act an \"insult\" to Catholics. Cardinal Murphy-O\'Connor, the leader of the Roman Catholic Church in England, pointed out that Prince William (later the Duke of Cambridge) \"can marry by law a Hindu, a Buddhist, anyone, but not a Roman Catholic.\" Opponents of repeal, such as Enoch Powell and Adrian Hilton, believe that it would lead to the disestablishment of the Church of England as the state religion if a Roman Catholic were to come to the throne. They also note that the monarch must swear to defend the faith and be a member of the Anglican Communion, but that a Roman Catholic monarch would, like all Roman Catholics, owe allegiance to the Pope. This would, according to opponents of repeal, amount to a loss of sovereignty for the Anglican Church.
When in December 1978 there was media speculation that Prince Charles might marry a Roman Catholic, Powell defended the provision that excludes Roman Catholics from ascending the throne, stating his objection was not rooted in religious bigotry but in political considerations. He said a Roman Catholic monarch would mean the acceptance of a source of authority external to the realm and \"in the literal sense, foreign to the Crown-in-Parliament \... Between Roman Catholicism and royal supremacy there is, as Saint Thomas More concluded, no reconciliation.\" Powell concluded that a Roman Catholic crown would be the destruction of the Church of England because \"it would contradict the essential character of that church.\"
He continued:
> When Thomas Hobbes wrote that \"the Papacy is no other than the ghost of the deceased Roman Empire sitting crowned upon the grave thereof\", he was promulgating an enormously important truth. Authority in the Roman Church is the exertion of that *imperium* from which England in the 16th century finally and decisively declared its national independence as the *alter imperium*, the \"other empire\", of which Henry VIII declared \"This realm of England is an empire\" \... It would signal the beginning of the end of the British monarchy. It would portend the eventual surrender of everything that has made us, and keeps us still, a nation.
The Scottish Parliament unanimously passed a motion in 1999 calling for the complete removal of any discrimination linked to the monarchy and the repeal of the Act of Settlement. The following year, *The Guardian* challenged the succession law in court, claiming that it violated the European Convention on Human Rights, which provides,
> The enjoyment of the rights and freedoms set forth in this Convention shall be secured without discrimination on any ground such as sex, race, colour, language, religion, political or other opinion, national or social origin, association with a national minority, property, birth, or other status.
As the Convention nowhere lists the right to succeed to the Crown as a human right, the challenge was rejected.
Adrian Hilton, writing in *The Spectator* in 2003, defended the Act of Settlement as not \"irrational prejudice or blind bigotry\", but claimed that it was passed because \"the nation had learnt that when a Roman Catholic monarch is upon the throne, religious and civil liberty is lost.\" He points to the Pope\'s claiming universal jurisdiction, and Hilton argues that \"it would be intolerable to have, as the sovereign of a Protestant and free country, one who owes any allegiance to the head of any other state\" and contends that, if such situation came about, \"we will have undone centuries of common law.\" He said that because the Roman Catholic Church does not recognise the Church of England as an apostolic church, a Roman Catholic monarch who abided by their faith\'s doctrine would be obliged to view Anglican and Church of Scotland archbishops, bishops, and clergy as part of the laity and therefore \"lacking the ordained authority to preach and celebrate the sacraments.\" (Hilton noted that the Church of Scotland\'s Presbyterian polity does not include bishops or archbishops.) Hilton said a Roman Catholic monarch would be unable to be crowned by the Archbishop of Canterbury and notes that other European states have similar religious provisions for their monarchs: Denmark, Norway, and Sweden, whose constitutions compel their monarchs to be Lutherans; the Netherlands, which has a constitution requiring its monarchs be members of the Protestant House of Orange; and Belgium, which has a constitution that provides for the succession to be through Roman Catholic houses.
In December 2004, a private member\'s bill---the Succession to the Crown Bill---was introduced in the House of Lords. The government, headed by Tony Blair, blocked all attempts to revise the succession laws, claiming it would raise too many constitutional issues and it was unnecessary at the time. In the British general election the following year, Michael Howard promised to work towards having the prohibition removed if the Conservative Party gained a majority of seats in the House of Commons, but the election was won by Blair\'s Labour Party. Four years later, plans drawn up by Chris Bryant were revealed that would end the exclusion of Catholics from the throne and end the doctrine of male-preference primogeniture in favour of absolute primogeniture, which governs succession solely on birth order and not on sex. The issue was raised again in January 2009, when a private member\'s bill to amend the Act of Succession was introduced in parliament.
| 941 |
Act of Settlement 1701
| 6 |
2,070 |
# Act of Settlement 1701
## Amendment proposals {#amendment_proposals}
### Across the realms {#across_the_realms}
In early 2011 Keith Vaz, a Labour Member of Parliament, introduced to the House of Commons at Westminster a private member\'s bill which proposed that the Act of Settlement be amended to remove the provisions relating to Roman Catholicism and change the primogeniture governing the line of succession to the British throne from male-preference to absolute cognatic. Vaz sought support for his project from the Canadian Cabinet and Prime Minister Stephen Harper, but the Office of the Prime Minister of Canada responded that the issue was \"not a priority for the government or for Canadians without further elaboration on the merits or drawbacks of the proposed reforms\". Stephenson King, Prime Minister of Saint Lucia, said he supported the idea and it was reported that the government of New Zealand did, as well. The Monarchist League of Canada said at the time to the media that it \"supports amending the Act of Settlement in order to modernize the succession rules.\"
Later the same year, the Deputy Prime Minister of the United Kingdom, Nick Clegg, announced that the government was considering a change in the law. At approximately the same time, it was reported that British Prime Minister David Cameron had written to each of the prime ministers of the other fifteen Commonwealth realms, asking for their support in changing the succession to absolute primogeniture and notifying them he would raise his proposals at that year\'s Commonwealth Heads of Government Meeting (CHOGM) in Perth, Australia. Cameron reportedly also proposed removing the restriction on successors being or marrying Roman Catholics; however, potential Roman Catholic successors would be required to convert to Anglicanism prior to acceding to the throne. In reaction to the letter and media coverage, Harper stated that, this time, he was \"supportive\" of what he saw as \"reasonable modernizations\".
At the 2011 Commonwealth Heads of Government Meeting on 28 October 2011, the prime ministers of the other Commonwealth realms agreed to support Cameron\'s proposed changes to the Act. The bill put before the Parliament of the United Kingdom would act as a model for the legislation required to be passed in at least some of the other realms, and any changes would only first take effect if the Duke of Cambridge were to have a daughter before a son.
The British group Republic asserted that succession reform would not make the monarchy any less discriminatory. As it welcomed the gender equality reforms, the British newspaper *The Guardian* criticized the lack of a proposal to remove the ban on Catholics sitting on the throne, as did Alex Salmond, First Minister of Scotland, who pointed out that \"It is deeply disappointing that the reform \[of the Act of Settlement of 1701\] has stopped short of removing the unjustifiable barrier on a Catholic becoming monarch.\" On the subject, Cameron asserted: \"Let me be clear, the monarch must be in communion with the Church of England because he or she is the head of that Church.\"
The disqualification arising from marriage to a Roman Catholic was removed by the Succession to the Crown Act 2013
| 524 |
Act of Settlement 1701
| 7 |
2,080 |
# A Fire Upon the Deep
***A Fire Upon the Deep*** is a 1992 science fiction novel by American writer Vernor Vinge. It is a space opera involving superhuman intelligences, aliens, variable physics, space battles, love, betrayal, genocide, and a communication medium resembling Usenet. *A Fire Upon the Deep* won the Hugo Award in 1993, sharing it with *Doomsday Book* by Connie Willis.
Besides the normal print book editions, the novel was also included on a CD-ROM sold by ClariNet Communications along with the other nominees for the 1993 Hugo awards. The CD-ROM edition included numerous annotations by Vinge on his thoughts and intentions about different parts of the book, and was later released as a standalone e-book. It has a loose prequel, *A Deepness in the Sky*, from 1999, and a direct sequel, *The Children of the Sky*, from 2012.
## Setting
The novel is set in various locations in the Milky Way. The galaxy is divided into four concentric volumes called the \"Zones of Thought\"; it is not clear to the novel\'s characters whether this is a natural phenomenon or an artificially produced one, but it seems to roughly correspond with galactic-scale stellar density and a Beyond region is mentioned in the Sculptor Galaxy as well. The Zones reflect fundamental differences in basic physical laws, and one of the main consequences is their effect on intelligence, both biological and artificial. Artificial intelligence and automation is most directly affected, in that advanced hardware and software from the Beyond or the Transcend will work less and less well as a ship \"descends\" towards the Unthinking Depths. But even biological intelligence is affected to a lesser degree. The four zones are spoken of in terms of \"low\" to \"high\" as follows:
- The **Unthinking Depths** are the innermost zone, surrounding the Galactic Center. In it, only minimal forms of intelligence, biological or otherwise, are possible. This means that any ship straying into the Depths will be stranded, effectively permanently. Even if the crew did not die immediately---and some forms of life native to \"higher\" Zones would likely do so---they would be rendered incapable of even human intelligence, leaving them unable to operate their ship in any meaningful way.
- Surrounding the Depths is the **Slow Zone**. \"Old Earth\" is in this Zone, and humanity is said to have originated there, although Earth plays no significant role in the story. Biological intelligence is possible in \"the Slowness\", but not true, sentient, artificial intelligence. Automation is not intelligent enough to calculate the jumps required for faster than light travel (FTL) in the Slow Zone, but they may escape by performing an immediate reverse jump to where they came from if the Slowness is detected, and navigation systems watch for this and store the information required during each jump. All ships in the Slow Zone are restricted to sub-light speeds. Faster-than-light communication is impossible into or out of the Slow Zone. As the boundaries of the Zones are subject to change, accidental entry into the Slow Zone is a major hazard at the \"Bottom\" of the Beyond, the next zone out. Starships which operate near the Beyond/Slow Zone border often have an auxiliary Bussard ramjet drive, so that if they accidentally stray into the Slow Zone (thus disabling any FTL drive), they will at least have a backup (sub-light) drive to try to reach the Beyond. Such ships also tend to include \"coldsleep\" equipment, as it is likely that any such return will still take many lifetimes for most species.
- The next layer outward is the **Beyond**, within which artificial intelligence and FTL travel and FTL communication are possible. A few human civilizations exist in the Beyond, all descended from a single ethnic Norwegian group which reached the Beyond. The original settlement of this group is known as Nyjora; other human settlements in the Beyond include Straumli Realm and Sjandra Kei. In the Beyond, FTL travel is accomplished by making many small \"jumps\" across space, with the efficiency of the drive increasing the farther a ship travels from the galactic core. This reflects increases in both drive efficiency and the ship\'s automation\'s increased capacity, enabling the computation of longer and longer jumps. The Beyond is not a homogeneous zone---many references are made to, e.g., the \"High Beyond\" or the \"Bottom of the Beyond\", depending on distance from the galactic core. These terms refer to differences in the Zone itself, not just relative distance from the Core, but there are no obvious Zone boundaries within the Beyond the way there are between the Slow Zone and the Beyond, or between the Beyond and the Transcend. Whereas a ship that crosses from the Beyond to the Slow Zone or vice versa will experience a dramatic change in its capabilities, a ship in the Beyond which moves farther out will experience a gradual increase in efficiency (assuming it has the technology to make use of it) until another major shift at the boundary with the Transcend. The Beyond is populated by a very large number of interstellar and intergalactic civilizations which are linked by an FTL communication network, \"the Net\", sometimes cynically called the \"Net of a Million Lies\". The Net does connect with the Transcend, on the off-chance that one of the \"Powers\" that live there deigns to communicate, but has no connections with the Slow Zone, as FTL communication is impossible into or out of that Zone. In the novel, the Net is depicted as working much like the Usenet network in the early 1990s, with transcripts of messages containing header and footer information as one would find in such forums.
- The outermost layer, containing the galactic halo, is the **Transcend**, within which incomprehensible, superintelligent beings dwell. When a \"Beyonder\" civilization reaches the point of technological singularity, it can \"Transcend\", becoming a \"Power\". Such Powers always seem to relocate to the Transcend, seemingly necessarily, where they become engaged in activities which are entirely mysterious to those in the Beyond.
One of the characters in the book, the human Ravna, uses this analogy to explain the relation between the zones:
| 1,016 |
A Fire Upon the Deep
| 0 |
2,080 |
# A Fire Upon the Deep
## Plot
An expedition from Straumli Realm, a young human civilization in the high Beyond, investigates a newly discovered five-billion-year-old data archive in the low Transcend that offers the possibility of unimaginable riches. The expedition\'s facility, High Lab, is gradually and secretly compromised by an initially dormant superintelligence within the archive later known as the Blight. However, shortly before the Blight\'s final \"flowering\", two self-aware entities, created similarly to the Blight, plot to aid the humans before the Blight can gain its full powers.
Finally recognizing their danger, the High Lab researchers attempt to flee in two ships, one carrying the adults and the second carrying the children in \"coldsleep boxes\". The Blight discovers that the first ship lists a data storage device in its cargo manifest; assuming it contains information that could harm it, the Blight destroys the ship. The second ship escapes.
The ship lands on a distant planet with a medieval-level civilization of dog-like creatures, dubbed \"Tines\", who live in packs as group minds. Upon landing, however, the two surviving adults, husband and wife, are ambushed and killed by Tine fanatics known as Flenserists, in whose realm they have landed. The Flenserists capture a young boy named Jefri Olsndot and his wounded sister, Johanna. Johanna is rescued by a Tine named Peregrine who witnessed the ambush and taken to a neighboring kingdom ruled by a brilliant Tine named Woodcarver. Steel, the Flenserists\' leader, tells Jefri that Johanna and their parents were killed by Woodcarver and exploits him in order to develop advanced technology (such as cannon and radio communication), while Johanna and the knowledge stored in her \"dataset\" device help Woodcarver rapidly develop as well. A highly placed Flenserist spy keeps Steel informed of Woodcarver\'s progress.
A distress signal from the sleeper ship eventually reaches \"Relay\", a major information/service provider for the galactic communications network. A benign transcendent being named \"Old One\" contacts Relay, seeking information about the Blight and the humans who released it, and reconstitutes a human man named Pham Nuwen from the wreckage of a spaceship to act as its agent, using his doubt of his own memory\'s veracity to keep him under its control. Ravna Bergsndot, the only human Relay employee, traces the sleeper ship\'s signal to the Tines\' world and persuades her employer to investigate what it took from High Lab, contracting the merchant vessel *Out of Band II*, owned by two sentient plant \"Skroderiders\", Blueshell and Greenstalk, to transport her and Pham there.
Before the mission is launched, the Blight launches a surprise attack on Relay and kills Old One. As Old One dies, it downloads what anti-Blight information it can into Pham. Pham, Ravna and the Skroderiders barely escape Relay\'s destruction in the *Out of Band II*.
The Blight expands, taking over races and \"rewriting\" their people to become its agents, murdering several other Powers, and seizing other archives in the Beyond, searching for what was taken from High Lab, but looks only in the Beyond. It finally realizes where the danger truly lies and sends a hastily assembled fleet in pursuit.
The humans arrive at the Tines\' world first and ally with Woodcarver to defeat the Flenserists and rescue Jefri. Pham then initiates Countermeasure, which was aboard the humans\' ship. Countermeasure extends the Slow Zone outward thousands of light years, enveloping and killing the Blight at the cost of wrecking thousands of civilizations and causing trillions of deaths. The humans are stranded on the Tines\' world, now in the depths of the Slow Zone. Activating Countermeasure is fatal to Pham, but before he dies, the remnant of Old One within his mind reveals to him that, although his body is a reconstruction, his memories are real. (Vinge expands on Pham\'s backstory in *A Deepness in the Sky*.)
| 634 |
A Fire Upon the Deep
| 1 |
2,080 |
# A Fire Upon the Deep
## Intelligent species {#intelligent_species}
### Aprahanti
A race of humanoids with colorful butterfly-like wings who attempt to use the chaos wrought by the Blight to reestablish their waning hegemony. Despite their attractive, delicate appearance, the Aprahanti are an extremely fearsome and vicious species.
### Blight
An ancient, malevolent super-intelligent entity which strives to constantly expand and can manipulate electronics and sentient beings.
### Dirokimes
An older race which originally inhabited Sjandra Kei before the arrival of humanity. They work with the humans.
### Humans
All humans in the novel (except Pham) are descended from Nyjoran stock. Their ancestors were \"Tuvo-Norsk\" asteroid miners from Old Earth\'s solar system, which is noted as being on the other side of the galaxy in the Slow Zone. (*Nyjora* sounds similar to New Norwegian \"New Earth\".) One of the major human habitations is Sjandra Kei, three systems comprising roughly 28 billion individuals. Their main language is Samnorsk, the Norwegian term for a hypothetical unification of the Bokmål and Nynorsk forms of the language. (Vinge indicates in the book\'s dedication that several key ideas in it came to him while at a conference in Tromsø, Norway.)
### Skroders/Riders/Skroderiders
A race of plant beings with fronds that serve as arms, the Riders have little native capacity for short-term memory. They are one of the longest-existing species; five billion years ago, someone gave them six-wheeled mechanical constructs (\"skrodes\") to move around and to provide short-term memory that made it easier for them to retain information well enough to become long-term memory in the \"rider\". It is later revealed that their \"benefactor\" is the Blight, which is able to easily corrupt and remotely operate the Riders via their skrodes.
### Tines
A race of group minds, each Tine is a \"pack\" of doglike members, which communicate within the pack using very short-range ultrasonic waves from drumlike organs called \"tympana\". A pack of four to eight members possesses roughly human-level intelligence; a pack with fewer or more is less smart. Each \"soul\" can survive and evolve by adding members to replace those who die, potentially for hundreds of years, as Woodcarver does.
## Related works {#related_works}
Vinge first used the concepts of \"Zones of Thought\" in a 1988 novella *The Blabber*, which occurs after *Fire*. Vinge\'s novel *A Deepness in the Sky* (1999) is a prequel to *A Fire Upon the Deep* set 20,000 years earlier and featuring Pham Nuwen. Vinge\'s *The Children of the Sky*, \"a near-term sequel to *A Fire Upon the Deep*{{-\"}}, set ten years later, was released in October 2011.
Vinge\'s former wife, Joan D. Vinge, has also written stories in the Zones of Thought universe, based on his notes. These include \"The Outcasts of Heaven Belt\", \"Legacy\", and (as of 2008) a planned novel featuring Pham Nuwen.
## Title
Vinge\'s original title for the novel was \"Among the Tines\"; its final title was suggested by his editors.
## Awards and nominations {#awards_and_nominations}
*A Fire Upon the Deep* shared the 1993 Hugo Award for Best Novel with *Doomsday Book*. The book was nominated for the Nebula Award for Best Novel of 1992, the 1993 John W. Campbell Memorial Award for Best Science Fiction Novel, and the 1993 Locus Award for Best Science Fiction Novel.
## Critical reactions {#critical_reactions}
Jo Walton wrote: \"Any one of the ideas in *A Fire Upon the Deep* would have kept an ordinary writer going for years. For me it\'s the book that does everything right, the example of what science fiction does when it works. \... *A Fire Upon the Deep* remains a favourite and a delight to re-read, absorbing even when I know exactly what\'s coming
| 612 |
A Fire Upon the Deep
| 2 |
2,093 |
# Abimelech
**Abimelech** (also spelled **Abimelek** or **Avimelech**; `{{Hebrew Name 2|אֲבִימֶלֶךְ|אֲבִימָלֶךְ|ʼAvīméleḵ|ʼAvīmáleḵ|ʼAḇīmeleḵ|ʼAḇīmāleḵ|"my father is a king"/"my father reigns"}}`{=mediawiki}) was the generic name given to all Philistine kings in the Hebrew Bible from the time of Abraham through King David. In the Book of Judges, Abimelech, son of Gideon, of the Tribe of Manasseh, is proclaimed king of Shechem after the death of his father.
## Etymology
The name or title *Abimelech* is formed from Canaanite words for \"father\" and \"king,\" and may be interpreted in a variety of ways, including \"Father-King\", \"My father is king,\" or \"Father of a king.\" In the Pentateuch, it is used as a title for kings in the land of Canaan.
Abimelech can be translated in Arabic as well into \"My father is king\", \"My father is owner\" or \"Father of a king,\" where *italic=no* (*أبي*) means father or my father while *italic=no* (*ملك*) means king or *italic=no* (*مالك*) for owner.
At the time of the Amarna tablets (mid-14th century BC), there was an Egyptian governor of Tyre similarly named Abimilki, `{{citation needed span|who is sometimes speculated to be connected with one or more of the biblical Abimelechs.|date=December 2021}}`{=mediawiki}
## `{{anchor|Abimelech of Gerar}}`{=mediawiki} Abimelech of Gerar {#abimelech_of_gerar}
Abimelech was most prominently the name of a polytheistic king of Gerar who is mentioned in two of the three wife--sister narratives in the Book of Genesis, in connection with both Abraham and Isaac.
King Abimelech of Gerar also appears in an extra-biblical tradition recounted in texts such as the *Arabic Apocalypse of Peter*, the *Cave of Treasures* and the *Conflict of Adam and Eve with Satan*, as one of twelve regional kings in Abraham\'s time said to have built the city of Jerusalem for Melchizedek.
| 287 |
Abimelech
| 0 |
2,093 |
# Abimelech
## Abimelech son of Jerubbaal/Gideon {#abimelech_son_of_jerubbaalgideon}
The Book of Judges mentions Abimelech, son of judge Gideon (also known as Jerubbaal). According to the biblical narrative, Abimelech was an extremely conniving and evil person. He persuaded his mother\'s brothers to encourage the people of Shechem to back him in a plot to overthrow his family rule and make him sole ruler.
After slaying all but one of his seventy brothers, Abimelech was crowned king. The brother who escaped, Jotham youngest son of Jerrubaal, made a pronouncement against Abimelech and those who had crowned him. The curse was that if they had not dealt righteously with the family of Jerrubaal, then fire would come against Abimelech from the people of Shechem and fire would come out of Abimelech against the people who had backed him in this bloody coup.
After Abimelech ruled for three years, the pronouncement came through. The people of Shechem set robbers to lie in wait of any goods or money headed to Abimelech and steal everything. Then Gaal Son of Ebed went to Shechem and drunkenly bragged that he would remove Abimelech from the throne. Zebul, ruler of Shechem, sent word to Abimelech along with a battle strategy. Once Zebul taunted Gaal into fighting Abimelech, he shut Gaal and his brethren out of the city.
Abimelech then slew the field workers that came out of the city of Shechem the next day. When he heard that the people of Shechem had locked themselves in a strong tower, he and his men set fire to it, killing about a thousand men and women.
After this, Abimelech went to Thebez and camped against it. When he went close to the tower in Thebez to set it on fire, a woman dropped an upper millstone on Abimelech\'s head. He did not want to be known as having been killed by a woman, so he asked his armour bearer to run him through with a sword. His place of death is cited as being Thebez.
## Russian use {#russian_use}
**Avimelekh** (*Авимеле́х*) is a Russian male first name derived from Abimelech. It was included into various, often handwritten, church calendars throughout the 17th--19th centuries, but was omitted from the official Synodal Menologium at the end of the 19th century.
## Other people with this name {#other_people_with_this_name}
Apart from the king (or kings) of Gerar, the Bible also records this name for:
- The father of Abiathar, and high priest in the time of David. In the parallel passage, the name is given as Ahimelech; most authorities consider this the more correct reading.
- The king of Gath better known as Achish, referred to as Abimelech or Achimelech in the title of Psalm 34.
- The husband of Naomi, and father of Mahlon and Chilion who leaves Bethlehem and dies in the land of Moab, in the Hebrew, his name is given as Elimelek, which is likely the correct reading.
Other literary references include:
- Abimélech, Satrap of Gaza is a character baritone in Camille Saint-Saëns\' *Samson and Delilah*
| 507 |
Abimelech
| 1 |
2,100 |
# Applesoft BASIC
**Applesoft BASIC** is a dialect of Microsoft BASIC, developed by Marc McDonald and Ric Weiland, supplied with Apple II computers. It supersedes Integer BASIC and is the BASIC in ROM in all Apple II series computers after the original Apple II model. It is also referred to as **FP BASIC** (from floating point) because of the Apple DOS command `FP` used to invoke it, instead of `INT` for Integer BASIC.
Applesoft BASIC was supplied by Microsoft and its name is derived from the names of both Apple Computer and Microsoft. Apple employees, including Randy Wigginton, adapted Microsoft\'s interpreter for the Apple II and added several features. The first version of Applesoft was released in 1977 on cassette tape and lacked proper support for high-resolution graphics. **Applesoft II**, which was made available on cassette and disk and in the ROM of the Apple II Plus and subsequent models, was released in 1978. It is this latter version, which has some syntax differences and support for the Apple II high-resolution graphics modes, that is usually synonymous with the term \"Applesoft.\"
## History
When Steve Wozniak wrote Integer BASIC for the Apple II, he did not implement support for floating-point arithmetic because he was primarily interested in writing games, a task for which integers alone were sufficient. In 1976, Microsoft had developed Microsoft BASIC for the MOS Technology 6502, but at the time there was no production computer that used it. Upon learning that Apple had a 6502 machine, Microsoft asked if the company were interested in licensing BASIC, but Steve Jobs replied that Apple already had one.
The Apple II was unveiled to the public at the West Coast Computer Faire in April 1977 and became available for sale in June. One of the most common customer complaints about the computer was BASIC\'s lack of floating-point math. Making things more problematic was that the rival Commodore PET personal computer had a floating point-capable BASIC interpreter from the beginning. As Wozniak---the only person who understood Integer BASIC well enough to add floating point features---was busy with the Disk II drive and controller and with Apple DOS, Apple turned to Microsoft.
Apple reportedly obtained an eight-year license for Applesoft BASIC from Microsoft for a flat fee of \$31,000, renewing it in 1985 through an arrangement that gave Microsoft the rights and source code for Apple\'s Macintosh version of BASIC. Applesoft was designed to be backwards-compatible with Integer BASIC and uses the core of Microsoft\'s 6502 BASIC implementation, which includes using the GET command for detecting key presses and not requiring any spaces on program lines. While Applesoft BASIC is slower than Integer BASIC, it has many features that the older BASIC lacks:
- Atomic strings: A string is no longer an array of characters (as in Integer BASIC and C); it is instead a garbage-collected object (as in Scheme and Java). This allows for string arrays; `{{code|DIM A$(10)|basic}}`{=mediawiki} creates an array of *eleven* string variables numbered 0--10.
- Multidimensional arrays (numbers or strings)
- Single-precision floating-point variables with an 8-bit exponent and a 31-bit significand and improved math capabilities, including trigonometry and logarithmic functions
- Commands for high-resolution graphics
- `DATA` statements, with `READ` and `RESTORE` commands, for representing numerical and string values in quantity
- `CHR$`, `STR$`, and `VAL` functions for converting between string and numeric types (both languages did have the `ASC` function)
- User-defined functions: simple one-line functions written in BASIC, with a single parameter
- Error-trapping: allowing BASIC programs to handle unexpected errors via subroutine written in BASIC
Conversely, Applesoft lacks the `MOD` (remainder) operator from Integer BASIC.
Adapting BASIC for the Apple II was a tedious job as Apple received a source listing for Microsoft 6502 BASIC which proved to be buggy and also required the addition of Integer BASIC commands. Since Apple had no 6502 assembler on hand, the development team was forced to send the source code over the phone lines to Call Computer, an outfit that offered compiler services. This was an extremely tedious, slow process and after Call Computer lost the source code due to an equipment malfunction, one of the programmers, Cliff Huston, used his own IMSAI 8080 computer to cross assemble the BASIC source.
| 704 |
Applesoft BASIC
| 0 |
2,100 |
# Applesoft BASIC
## Features
Applesoft is similar to Commodore\'s BASIC 2.0 aside from features inherited from Integer BASIC. There are a few minor differences such as Applesoft\'s lack of bitwise operators; otherwise most BASIC programs that do not use hardware-dependent features will run on both BASICs.
The `{{mono|PR#}}`{=mediawiki} statement redirects output to an expansion card, and `{{mono|IN#}}`{=mediawiki} redirects input from an expansion card. The slot number of the card is specified after the `{{mono|PR#}}`{=mediawiki} or `{{mono|IN#}}`{=mediawiki} within the statement. The computer locks-up if there is no card present in the slot. `{{mono|PR#0}}`{=mediawiki} restores output to the 40 column screen and `{{mono|IN#0}}`{=mediawiki} to the keyboard.
The `{{mono|PR#}}`{=mediawiki} statement can be used to redirect output to the printer (e.g. `{{code|2=basic|10 PR#x:PRINT"Hello!"}}`{=mediawiki}) where x is the slot number containing the printer port card. To send a BASIC program listing to the printer, the user types `{{code|PR#x:LIST}}`{=mediawiki}.
Using `{{mono|PR#}}`{=mediawiki} on a slot with a disk drive (usually in slot 6) causes Applesoft to boot the disk drive. Using `{{mono|PR#}}`{=mediawiki} on a slot with an 80 column card (usually in slot 3) switches to 80 column text mode.
As with Commodore BASIC, numeric variables are stored as 40-bit floating point; each variable requires five bytes of memory. The programmer may designate variables as integer by following them with a percent sign, in which case they use two bytes and are limited to a range of -32768 to 32767; however BASIC internally converts them back to floating point when performing calculations, while each percent sign also takes an additional byte of program code, so in practice this feature is only useful for reducing the memory usage of large array variables, as it offers no performance benefit.
The RND function generates a pseudorandom fractional number between 0 and 1. `{{code|RND(0)}}`{=mediawiki} returns the most recently generated random number. `{{mono|RND}}`{=mediawiki} with a negative number will jump to a point in the sequence determined by the particular negative number used. RND with any positive value generates the next number in the sequence, not dependent on the actual value given.
Like other implementations of Microsoft BASIC, Applesoft discards spaces (outside of strings and comments) on program lines. `LIST` adds spaces when displaying code for the sake of readability. Since `{{mono|LIST}}`{=mediawiki} adds a space before and after every tokenized keyword, it often produces two spaces in a row where one would suffice for readability.
The default prompt for `INPUT` is a question mark. `PRINT` does not add a leading space in front of numbers.
### Limitations
Through several early models of the Apple II, Applesoft BASIC did not support the use of lowercase letters in programs, except in strings. `PRINT` is a valid command but `print` and `Print` result in a syntax error.
Applesoft lacks several commands and functions common to most of the non-6502 Microsoft BASIC interpreters, such as:
- `INSTR` (search for a substring in a string)
- `PRINT USING` (format numbers in printed output)
- `INKEY$` (check for a keypress without stopping the program; although a PEEK to location \$C000 achieves this action)
- `LPRINT` (output to a printer instead of the screen)
Applesoft does not have commands for file or disk handling, other than to save and load programs via cassette tape. The Apple II disk operating system, known simply as DOS, augments the language to provide such abilities.
Only the first two letters of variables names are significant. For example, \"LOW\" and \"LOSS\" are treated as the same variable, and attempting to assign a value to \"LOSS\" overwrites any value assigned to \"LOW\". A programmer also has to avoid consecutive letters that are Applesoft commands or operations. The name \"SCORE\" for a variable is interpreted as containing the `OR` Boolean operator, rendered as `SC OR E`. \"BACKGROUND\" contains `GR`, the command to invoke the low-resolution graphics mode, and results in a syntax error.
### Sound and graphics {#sound_and_graphics}
The only sound support is the option to `PRINT` an ASCII bell character to sound the system alert beep, and a `PEEK` command to click the speaker. The language is not fast enough to produce more than a baritone buzz from repeated clicks. Programs can, however, store a machine-language routine to be called to generate electronic musical tones spanning several octaves.
Applesoft supports drawing in the Apple II\'s low resolution and high resolution modes. There are commands to plot pixels and draw horizontal and vertical lines in low resolution. High resolution allows arbitrary lines and vector-based shape tables for drawing scaled and rotated objects. The only provision for mixing text and graphics is the four lines of text at the bottom of a graphic display.
Beginning with the Apple IIe, a \"double-high resolution\" mode became available on machines with 128k of memory. This mode essentially duplicates the resolution of the original high resolution mode, but including all 16 colors of the low resolution palette. Applesoft does not provide direct support for this mode. Apple IIGS-specific modes are likewise not supported.
### Extensions
Applesoft BASIC can be extended by two means: the ampersand (`{{mono|&}}`{=mediawiki}) command and the `{{mono|USR()}}`{=mediawiki} function. These are two features that call low-level machine-language routines stored in memory, which is useful for routines that need to be fast or require direct access to arbitrary functions or data in memory. The `{{mono|USR()}}`{=mediawiki} function takes one argument, and can be programmed to derive and return a calculated function value to be used in a numerical expression. `{{code|&}}`{=mediawiki} is effectively a shorthand for `{{mono|CALL}}`{=mediawiki}, with an address that is predefined. By calling routines in the Applesoft ROM, it is possible for ampersand routines to parse values that follow the ampersand. Numerous third-party commercial packages were available to extend Applesoft using ampersand routines.
| 943 |
Applesoft BASIC
| 1 |
2,100 |
# Applesoft BASIC
## Features
### Bugs
A deficiency with error-trapping via `ONERR` means that the system stack is not reset if an error-handling routine does not invoke `RESUME`, potentially leading to a crash. The built-in pseudorandom number generator function `RND` is capable of producing a predictable series of outputs due to the manner in which the generator is seeded when first powering on. This behavior is contrary to how Apple\'s documentation describes the function.
### Performance
Wozniak originally referred to his Integer BASIC as \"Game BASIC\" (having written it so he could implement a *Breakout* clone for his new computer). Few action games were written in Applesoft BASIC, in large part because the use of floating-point numbers for all math operations degrades performance.
Applesoft BASIC programs are stored as a linked list of lines; a `GOTO` or `GOSUB` takes linear time. Some programs have the subroutines at the top to reduce the time for calling them.
Unlike Integer BASIC, Applesoft does not convert literal numbers (like 100) in the source code to binary when a line is entered. Rather, the ASCII string is converted whenever the line is executed. Since variable lookup is often faster than this conversion, it can be faster to store numeric constants used inside loops in variables before the loop is entered.
| 217 |
Applesoft BASIC
| 2 |
2,100 |
# Applesoft BASIC
## Sample code {#sample_code}
Hello, World! in Applesoft BASIC can be entered as the following:
``` cbmbas
10TEXT:HOME
20?"HELLO WORLD"
```
Multiple commands can be included on the same line of code if separated by a colon (`:`). The `?` can be used in Applesoft BASIC (and almost all versions of Microsoft BASIC) as a shortcut for \"PRINT\", though spelling out the word is not only acceptable but canonical---Applesoft converted \"?\" in entered programs to the same token as \"PRINT\" (thus no memory is actually saved by using \"?\"), thus either appears as \"PRINT\" when a program is listed. The program above appears in a `LIST` command as:
``` cbmbas
10 TEXT : HOME
20 PRINT "HELLO WORLD"
```
When Applesoft II BASIC was initially released in mid-1978, it came on cassette tape and could be loaded into memory via the Apple II\'s machine language monitor. When the enhanced Apple II+ replaced the original II in 1979, Applesoft was now included in ROM and automatically started on power-up if no bootable floppy disk was present. Conversely, Integer BASIC was now removed from ROM and turned into an executable file on the DOS 3.3 disk.
## Early evolution {#early_evolution}
The original Applesoft, stored in RAM as documented in its Reference Manual of November 1977, has smaller interpreter code than the later Applesoft II, occupying 8½ KB of memory, instead of the 10 KB used by the later Applesoft II. Consequently, it lacks a number of command features developed for the later, mainstream version:
- All commands supporting Apple\'s \"high resolution\" graphics (9 total)
- Error-trapping with ONERR\...GOTO and RESUME
- Machine-routine shorthand call \"&\"
- Screen-clearing HOME (a call to a system ROM routine)
- Text-output control NORMAL, INVERSE, FLASH and SPEED=
- The print-space function SPC() is listed among reserved words in the manual, but is not otherwise documented (the TAB() print-function *is* documented)
- Cassette tape storage of numerical arrays: STORE and RECALL
- Device response: WAIT
as well as several the later version would have, that had already been present in Apple\'s Integer BASIC:
- Program-line deletion: DEL
- Machine-routine access: CALL
- Peripheral device access: IN# and PR# (although IN without \"#\" is listed among reserved words)
- Memory range control: HIMEM: and LOMEM:
- Execution tracking for debugging: TRACE and NOTRACE
- Screen-positioning: HTAB and VTAB
- Subroutine aborting POP
- Functions PDL() to read the analog controllers, and SCRN() to read the low-resolution graphics screen (both accessing system ROM routines)
In addition, its low-resolution graphics commands have different names from their Integer BASIC/Applesoft II counterparts. All command names are of the form PLTx such that GR, COLOR=, PLOT, HLIN and VLIN are called PLTG, PLTC, PLTP, PLTH, and PLTV, respectively. The command for returning to text mode, known as TEXT in other versions, is simply TEX, and carries the proviso that it has to be the last statement in a program line.
Applesoft BASIC 1.x was closer to Microsoft\'s original 6502 BASIC code than the later Applesoft II; it retained the Memory Size? prompt and displayed a Microsoft copyright notice. To maintain consistency with Integer BASIC, the \"Ok\" prompt from Microsoft\'s code was replaced by a \] character. Applesoft 1.x also prompted the user upon loading if they wished to disable the REM statement and the LET keyword in assignment statements in exchange for lores graphics commands.
The USR() function is also defined differently, serving as a stand-in for the absent CALL command. Its argument is not for passing a numerical value to the machine-language routine, but is instead the call-address of the routine itself; there is no \"hook\" to pre-define the address. All of several examples in the manual use the function only to access \"system monitor ROM\" routines, or short user-routines to manipulate the ROM routines. No mention is made of any code to calculate the value returned by the function itself; the function is always shown being assigned to \"dummy\" variables, which, without action to set a value by user-code, just receive a meaningless value handed back to them. Even accessed ROM routines that return values (in examples, those that provide the service of PDL() and SCRN() functions) merely have their values stored, by user-routines, in locations that are separately PEEKed in a subsequent statement.
Unlike in Integer BASIC and Applesoft II, the Boolean operators AND, OR and NOT perform bitwise operations on 16-bit integer values. If they are given values outside that range, an error results.
The terms OUT and PLT (and the aforementioned IN) appear in the list of reserved words, but are not explained anywhere in the manual.
## Related BASICs {#related_basics}
Several compilers for Applesoft BASIC exist, including TASC (The Applesoft Compiler) from Microsoft in 1981.
Coleco claimed that its Adam home computer\'s SmartBASIC was source-code compatible with Applesoft.
Microsoft licensed a BASIC compatible with Applesoft to VTech for its Laser 128 clone
| 818 |
Applesoft BASIC
| 3 |
2,108 |
# Adalbert of Prague
**Adalbert of Prague** (*Sanctus Adalbertus*, *svatý Vojtěch*, *svätý Vojtech*, *święty Wojciech*, *Szent Adalbert (Béla)*; c. 956`{{snd}}`{=mediawiki}23 April 997), known in the Czech Republic, Poland and Slovakia by his birth name **Vojtěch** (*Voitecus*), was a Czech missionary and Christian saint. He was the Bishop of Prague and a missionary to the Hungarians, Poles, and Prussians, who was martyred in his efforts to convert the Baltic Prussians to Christianity. He is said to be the composer of the oldest Czech hymn *Hospodine, pomiluj ny* and *Bogurodzica*, the oldest known Polish anthem but his authorship of them has not been confirmed.
Adalbert was later declared the patron saint of the Czech Republic, Poland, and the Duchy of Prussia. He is also the patron saint of the Archdiocese of Esztergom in Hungary.
## Life
### Early years {#early_years}
Born as *Vojtěch* in 952 or c. 956 in gord Libice, he belonged to the Slavnik clan, one of the two most powerful families in Bohemia. Events from his life were later recorded by a Bohemian priest Cosmas of Prague (1045--1125). Vojtěch\'s father was Slavník (d. 978--981), a duke ruling a province centred at Libice. His mother was Střezislava (d. 985--987), and according to David Kalhous belonged to the Přemyslid dynasty. He had five brothers: Soběslav, Spytimír, Dobroslav, Pořej, and Čáslav. Cosmas also refers to Radim (later Gaudentius) as a brother; who is believed to have been a half-brother by his father\'s liaison with another woman. After he survived a grave illness in childhood, his parents decided to dedicate him to the service of God. Adalbert was well educated, having studied for approximately ten years (970--80) in Magdeburg under Adalbert of Magdeburg. The young Vojtěch took his tutor\'s name \"Adalbert\" at his Confirmation.
### Episcopacy
In 981 Adalbert of Magdeburg died, and his young protege Adalbert returned to Bohemia. Later Bishop Dietmar of Prague ordained him a Catholic priest. In 982, Bishop Dietmar died, and Adalbert, despite being under canonical age, was chosen to succeed him as Bishop of Prague. Amiable and somewhat worldly, he was not expected to trouble the secular powers by making excessive claims for the Church. Although Adalbert was from a wealthy family, he avoided comfort and luxury, and was noted for his charity and austerity. After six years of preaching and prayer, he had made little headway in evangelising the Bohemians, who maintained deeply embedded pagan beliefs.
Adalbert opposed the participation of Christians in the slave trade and complained of polygamy and idolatry, which were common among the people. Once he started to propose reforms he was met with opposition from both the secular powers and the clergy. His family refused to support Duke Boleslaus in an unsuccessful war against Poland. Adalbert was no longer welcome and eventually forced into exile. In 988 he went to Rome. He lived as a hermit at the Benedictine monastery of Saint Alexis. Five years later, Boleslaus requested that the Pope send Adalbert back to Prague, in hopes of securing his family\'s support. Pope John XV agreed, with the understanding that Adalbert was free to leave Prague if he continued to encounter entrenched resistance. Adalbert returned as bishop of Prague, where he was initially received with demonstrations of apparent joy. Together with a group of Italian Benedictine monks which brought with him, he founded in 14 January 993 a monastery in Břevnov (then situated westward from Prague, now part of the city), the second oldest monastery on Czech territory.
In 995, the Slavniks\' former rivalry with the Přemyslids, who were allied with the powerful Bohemian clan of the Vršovids, resulted in the storming of the Slavnik town of Libice nad Cidlinou, which was led by the Přemyslid Boleslaus II the Pious. During the struggle four or five of Adalbert\'s brothers were killed. The Zlič Principality became part of the Přemyslids\' estate. Adalbert unsuccessfully attempted to protect a noblewoman caught in adultery. She had fled to a convent, where she was killed. In upholding the right of sanctuary, Bishop Adalbert responded by excommunicating the murderers. Butler suggests that the incident was orchestrated by enemies of his family.
After this, Adalbert could not safely stay in Bohemia and escaped from Prague. Strachkvas was eventually appointed to be his successor. However, Strachkvas suddenly died during the liturgy at which he was to accede to his episcopal office in Prague. The cause of his death is still ambiguous. The Pope directed Adalbert to resume his see, but believing that he would not be allowed back, Adalbert requested a brief as an itinerant missionary.
Adalbert then traveled to Hungary and probably baptized Géza of Hungary and his son Stephen in Esztergom. Then he went to Poland where he was cordially welcomed by then-Duke Boleslaus I and installed as Bishop of Gniezno.
| 795 |
Adalbert of Prague
| 0 |
2,108 |
# Adalbert of Prague
## Life
### Mission and martyrdom in Prussia {#mission_and_martyrdom_in_prussia}
Adalbert again relinquished his diocese, namely that of Gniezno, and set out as a missionary to preach to the inhabitants near Prussia. Bolesław I, Duke (and, later, King) of Poland, sent soldiers with Adalbert on his mission to the Prussians. The Bishop and his companions, entered Prussian territory and traveled along the coast of the Baltic Sea to Gdańsk. At the borders of the Polish realm, at the mouth of the Vistula River, his half-brother Radim (Gaudentius), Benedict-Bogusza (who was probably a Pole), and at least one interpreter, ventured out into Prussia alone, as Bolesław had only sent his soldiers to escort them to the border.
Adalbert achieved some success upon his arrival, however his arrival mostly caused strain upon the local Prussian populations. Partially this was because of the imperious manner with which he preached, but potentially because he preached utilizing a book. The Prussians had an oral society where communication was face to face. To the locals Adalbert reading from a book may have come off as a manifestation of an evil action. He was forced to leave this first village after being struck in the back of the head by an oar by a local chieftain, causing the pages of his book to scatter upon the ground. He and his companions then fled across a river.
In the next place that Adalbert tried to preach, his message was met with the locals banging their sticks upon the ground, calling for the death of Adalbert and his companions. Retreating once again Adalbert and his companions went to a market place of Truso (near modern-day Elbląg). Here they were met with a similar response as at the previous place. On the 23 April 997, after mass, while Adalbert and his companions lay in the grass while eating a snack, they were set upon by a pagan mob. The mob was led by a man named Sicco, possibly a pagan priest, who delivered the first blow against Adalbert, before the others joined in. They removed Adalbert\'s head from his body after he was dead, and mounted on a pole while they returned home. This encounter may also have taken place in Tenkitten and Fischhausen (now Primorsk, Kaliningrad Oblast, Russia). It is recorded that his body was bought back for its weight in gold by King Boleslaus I of Poland.
| 402 |
Adalbert of Prague
| 1 |
2,108 |
# Adalbert of Prague
## Veneration and relics {#veneration_and_relics}
A few years after his martyrdom, Adalbert was canonized as **Saint Adalbert of Prague.** His life was written in *Vita Sancti Adalberti Pragensis* by various authors, the earliest being traced to imperial Aachen and the Bishop of Liège, Notger von Lüttich, although it was previously assumed that the Roman monk John Canaparius wrote the first *Vita* in 999. Another famous biographer of Adalbert was Bruno of Querfurt who wrote a hagiography of him in 1001--4.
Notably, the Přemyslid rulers of Bohemia initially refused to ransom Adalbert\'s body from the Prussians who murdered him, and therefore it was purchased by Poles. This fact may be explained by Adalbert\'s belonging to the Slavniks family which was rival to the Přemyslids. Thus Adalbert\'s bones were preserved in Gniezno, which assisted Boleslaus I of Poland in increasing Polish political and diplomatic power in Europe.
According to Bohemian accounts, in 1039 the Bohemian Duke Bretislav I looted the bones of Adalbert from Gniezno in a raid and translated them to Prague. According to Polish accounts, however, he stole the wrong relics, namely those of Gaudentius, while the Poles concealed Adalbert\'s relics which remain in Gniezno. In 1127 his severed head, which was not in the original purchase according to *Roczniki Polskie*, was discovered and translated to Gniezno. In 1928, one of the arms of Adalbert, which Bolesław I had given to Holy Roman Emperor Otto III in 1000, was added to the bones preserved in Gniezno. Therefore, today Adalbert has two elaborate shrines in the Prague Cathedral and Royal Cathedral of Gniezno, each of which claims to possess his relics, but which of these bones are his authentic relics is unknown. For example, pursuant to both claims two skulls are attributed to Adalbert. The one in Gniezno was stolen in 1923.
The massive bronze doors of Gniezno Cathedral, dating from around 1175, are decorated with eighteen reliefs of scenes from Adalbert\'s life. They are the only Romanesque ecclesiastical doors in Europe depicting a cycle illustrating the life of a saint, and therefore are a precious relic documenting Adalbert\'s martyrdom. We can read that door literally and theologically.
The one thousandth anniversary of Adalbert\'s martyrdom was on 23 April 1997. It was commemorated in Poland, the Czech Republic, Germany, Russia, and other nations. Representatives of Catholic, Eastern Orthodox, and Evangelical churches traveled on a pilgrimage to Adalbert\'s tomb located in Gniezno. Pope John Paul II visited the cathedral and celebrated a liturgy there in which heads of seven European nations and approximately one million faithful participated.
A ten-meter cross was erected near the village of Beregovoe (formerly Tenkitten), Kaliningrad Oblast, where Adalbert is thought to have been martyred by the Prussians.
| 454 |
Adalbert of Prague
| 2 |
2,108 |
# Adalbert of Prague
## Feast day {#feast_day}
- 25 January -- commemoration of translation of relics to Church of Saint Roch,
- 22 April -- commemoration in Diocese of Innsbruck,
- 22 April -- commemoration in Catholic Church in England and Wales,
- 23 April -- commemoration of death anniversary,
- 14 May -- commemoration of consecration of church in Aachen
- 25 August -- commemoration of translation of relics from Gniezno to Prague (1039)
- 26 August -- commemoration of translation of relics to Wrocław
- 20 October -- commemoration of translation of relics to Gniezno (1090)
- 22 October -- commemoration of translation of relics to Gniezno
- 6 November -- commemoration of translation of relics to Esztergom,
He is also commemorated on 23 April by Evangelical Church in Germany and Eastern Orthodox Church.
## In popular culture and society {#in_popular_culture_and_society}
The Dagmar and Václav Havel VIZE 97 Foundation Prize, given annually to a distinguished thinker \"whose work exceeds the traditional framework of scientific knowledge, contributes to the understanding of science as an integral part of general culture and is concerned with unconventional ways of asking fundamental questions about cognition, being and human existence\" includes a massive replica of Adalbert\'s crozier by Czech artist Jiří Plieštík.
St. Vojtech Fellowship was established in 1870 by Slovak Catholic priest Andrej Radlinský. It had facilitated Slovak Catholic thinkers and authors, continuing to publish religious original works and translations to this day. It is the official publishing body of Episcopal Conference of Slovakia.
### Churches and parishes named for Adalbert {#churches_and_parishes_named_for_adalbert}
St
| 261 |
Adalbert of Prague
| 3 |
2,110 |
# Ælfheah of Canterbury
**Ælfheah** (c. 953 -- 19 April 1012), more commonly known today as **Alphege**, was an Anglo-Saxon Bishop of Winchester, later Archbishop of Canterbury. He became an anchorite before being elected abbot of Bath Abbey. His reputation for piety and sanctity led to his promotion to the episcopate and, eventually, to his becoming archbishop. Ælfheah furthered the cult of Dunstan and also encouraged learning. He was captured by Viking raiders in 1011 during the siege of Canterbury and killed by them the following year after refusing to allow himself to be ransomed. Ælfheah was canonised as a saint in 1078. Thomas Becket, a later Archbishop of Canterbury, prayed to Ælfheah just before his murder in Canterbury Cathedral in 1170.
## Life
Ælfheah was born around 953, and became a monk early in life. He first entered the monastery of Deerhurst, but then moved to Bath, where he became an anchorite. He was noted for his piety and austerity and rose to become abbot of Bath Abbey. The 12th-century chronicler, William of Malmesbury recorded that Ælfheah was a monk and prior at Glastonbury Abbey, but this is not accepted by all historians. Indications are that Ælfheah became abbot at Bath by 982, perhaps as early as around 977. He perhaps shared authority with his predecessor Æscwig after 968.
Probably due to the influence of Dunstan, the Archbishop of Canterbury (959--988), Ælfheah was elected Bishop of Winchester in 984, and was consecrated on 19 October that year. While bishop, he was largely responsible for the construction of a large organ in the cathedral, audible from over a mile (1600 m) away and said to require more than 24 men to operate. He also built and enlarged the city\'s churches, and promoted the cult of Swithun and his predecessor, Æthelwold of Winchester. One act promoting Æthelwold\'s cult was the translation of Æthelwold\'s body to a new tomb in the cathedral at Winchester, which Ælfheah presided over on 10 September 996.
Following a Viking raid in 994, a peace treaty was agreed with one of the raiders, Olaf Tryggvason. Besides receiving danegeld, Olaf converted to Christianity and undertook never to raid or fight the English again. Ælfheah may have played a part in the treaty negotiations, and it is certain that he confirmed Olaf in his new faith.
In 1006, Ælfheah succeeded Ælfric as Archbishop of Canterbury, taking Swithun\'s head with him as a relic for the new location. He went to Rome in 1007 to receive his pallium---symbol of his status as an archbishop---from Pope John XVIII, but was robbed during his journey. While at Canterbury, he promoted the cult of Dunstan, ordering the writing of the second *Life of Dunstan*, which Adelard of Ghent composed between 1006 and 1011. He also introduced new practices into the liturgy, and was instrumental in the Witenagemot\'s recognition of Wulfsige of Sherborne as a saint in about 1012.
Ælfheah sent Ælfric of Eynsham to Cerne Abbey to take charge of its monastic school. He was present at the council of May 1008 at which Wulfstan II, Archbishop of York, preached his *Sermo Lupi ad Anglos* (*The Sermon of the Wolf to the English*), castigating the English for their moral failings and blaming the latter for the tribulations afflicting the country.
In 1011, the Danes again raided England, and from 8--29 September they laid siege to Canterbury. Aided by the treachery of Ælfmaer, whose life Ælfheah had once saved, the raiders succeeded in sacking the city. Ælfheah was taken prisoner and held captive for seven months. Godwine (Bishop of Rochester), Leofrun (abbess of St Mildrith\'s), and the king\'s reeve, Ælfweard were captured also, but the abbot of St Augustine\'s Abbey, Ælfmær, managed to escape. Canterbury Cathedral was plundered and burned by the Danes following Ælfheah\'s capture.
## Death
Ælfheah refused to allow a ransom to be paid for his freedom, and as a result was killed on 19 April 1012 at Greenwich, reputedly on the site of St Alfege\'s Church. The account of Ælfheah\'s death appears in the E version of the *Anglo-Saxon Chronicle*:
Ælfheah was the first Archbishop of Canterbury to die a violent death. A contemporary report tells that Thorkell the Tall attempted to save Ælfheah from the mob about to kill him by offering everything he owned except for his ship, in exchange for Ælfheah\'s life; Thorkell\'s presence is not mentioned in the *Anglo-Saxon Chronicle*, however. Some sources record that the final blow, with the back of an axe, was delivered as an act of kindness by a Christian convert known as \"Thrum\". Ælfheah was buried in Old St Paul\'s Cathedral. In 1023, his body was moved by King Cnut to Canterbury, with great ceremony. Thorkell the Tall was appalled at the brutality of his fellow raiders, and switched sides to the English king Æthelred the Unready following Ælfheah\'s death.
| 809 |
Ælfheah of Canterbury
| 0 |
2,110 |
# Ælfheah of Canterbury
## Veneration
thumb\|upright=.8\|An 1868 statue on the West Front of Salisbury Cathedral by James Redfern, showing Ælfheah holding the stones used in his martyrdom. Pope Gregory VII canonised Ælfheah in 1078, with a feast day of 19 April. Lanfranc, the first post-Conquest archbishop, was dubious about some of the saints venerated at Canterbury. He was persuaded of Ælfheah\'s sanctity, but Ælfheah and Augustine of Canterbury were the only pre-conquest Anglo-Saxon archbishops kept on Canterbury\'s calendar of saints. Ælfheah\'s shrine, which had become neglected, was rebuilt and expanded in the early 12th century under Anselm of Canterbury, who was instrumental in retaining Ælfheah\'s name in the church calendar. After the 1174 fire in Canterbury Cathedral, Ælfheah\'s remains, together with those of Dunstan were placed around the high altar, at which Thomas Becket is said to have commended his life into Ælfheah\'s care shortly before his martyrdom during the Becket controversy. The new shrine was sealed in lead, and was north of the high altar, sharing the honour with Dunstan\'s shrine, which was located south of the high altar. A *Life of Saint Ælfheah* in prose and verse was written by a Canterbury monk named Osbern, at Lanfranc\'s request. The prose version has survived, but the *Life* is very much a hagiography; many of the stories it contains have obvious Biblical parallels, making them suspect as a historical record.
In the late medieval period, Ælfheah\'s feast day was celebrated in Scandinavia, perhaps because of the saint\'s connection with Cnut. Few church dedications to him are known, with most of them occurring in Kent and one each in London and Winchester; as well as St Alfege\'s Church in Greenwich, a nearby hospital (1931--1968) was named after him. In the town of Solihull in the West Midlands, St Alphege Church is dedicated to Ælfheah dating back to approximately 1277. In 1929, a new Roman Catholic church in Bath, the Church of Our Lady & St Alphege, was designed by Giles Gilbert Scott in homage to the ancient Roman church of Santa Maria in Cosmedin, and dedicated to Ælfheah under the name of Alphege.
Artistic representations of Ælfheah often depict him holding a pile of stones in his chasuble, a reference to his martyrdom
| 373 |
Ælfheah of Canterbury
| 1 |
2,112 |
# Associative algebra
In mathematics, an **associative algebra** *A* over a commutative ring (often a field) *K* is a ring *A* together with a ring homomorphism from *K* into the center of *A*. This is thus an algebraic structure with an addition, a multiplication, and a scalar multiplication (the multiplication by the image of the ring homomorphism of an element of *K*). The addition and multiplication operations together give *A* the structure of a ring; the addition and scalar multiplication operations together give *A* the structure of a module or vector space over *K*. In this article we will also use the term *K*-algebra to mean an associative algebra over *K*. A standard first example of a *K*-algebra is a ring of square matrices over a commutative ring *K*, with the usual matrix multiplication.
A **commutative algebra** is an associative algebra for which the multiplication is commutative, or, equivalently, an associative algebra that is also a commutative ring.
In this article associative algebras are assumed to have a multiplicative identity, denoted 1; they are sometimes called **unital associative algebras** for clarification. In some areas of mathematics this assumption is not made, and we will call such structures non-unital associative algebras. We will also assume that all rings are unital, and all ring homomorphisms are unital.
Every ring is an associative algebra over its center and over the integers.
## Definition
Let *R* be a commutative ring (so *R* could be a field). An **associative *R*-algebra *A*** (or more simply, an ***R*-algebra *A***) is a ring *A* that is also an *R*-module in such a way that the two additions (the ring addition and the module addition) are the same operation, and scalar multiplication satisfies
: $r\cdot(xy) = (r\cdot x)y = x(r\cdot y)$
for all *r* in *R* and *x*, *y* in the algebra. (This definition implies that the algebra, being a ring, is unital, since rings are supposed to have a multiplicative identity.)
Equivalently, an associative algebra *A* is a ring together with a ring homomorphism from *R* to the center of *A*. If *f* is such a homomorphism, the scalar multiplication is `{{nowrap|(''r'', ''x'') ↦ ''f''(''r'')''x''}}`{=mediawiki} (here the multiplication is the ring multiplication); if the scalar multiplication is given, the ring homomorphism is given by `{{nowrap|''r'' ↦ ''r'' ⋅ 1<sub>''A''</sub>}}`{=mediawiki}. (See also *`{{slink|#From ring homomorphisms}}`{=mediawiki}* below).
Every ring is an associative **Z**-algebra, where **Z** denotes the ring of the integers.
A **`{{vanchor|commutative algebra}}`{=mediawiki}** is an associative algebra that is also a commutative ring.
### As a monoid object in the category of modules {#as_a_monoid_object_in_the_category_of_modules}
The definition is equivalent to saying that a unital associative *R*-algebra is a monoid object in ***R*-Mod** (the monoidal category of *R*-modules). By definition, a ring is a monoid object in the category of abelian groups; thus, the notion of an associative algebra is obtained by replacing the category of abelian groups with the category of modules.
Pushing this idea further, some authors have introduced a \"generalized ring\" as a monoid object in some other category that behaves like the category of modules. Indeed, this reinterpretation allows one to avoid making an explicit reference to elements of an algebra *A*. For example, the associativity can be expressed as follows. By the universal property of a tensor product of modules, the multiplication (the *R*-bilinear map) corresponds to a unique *R*-linear map
: $m : A \otimes_R A \to A$.
The associativity then refers to the identity:
: $m \circ ({\operatorname{id}} \otimes m) = m \circ (m \otimes \operatorname{id}).$
### From ring homomorphisms {#from_ring_homomorphisms}
An associative algebra amounts to a ring homomorphism whose image lies in the center. Indeed, starting with a ring *A* and a ring homomorphism `{{nowrap|''η'' : ''R'' → ''A''}}`{=mediawiki} whose image lies in the center of *A*, we can make *A* an *R*-algebra by defining
: $r\cdot x = \eta(r)x$
for all `{{nowrap|''r'' ∈ ''R''}}`{=mediawiki} and `{{nowrap|''x'' ∈ ''A''}}`{=mediawiki}. If *A* is an *R*-algebra, taking `{{nowrap|1=''x'' = 1}}`{=mediawiki}, the same formula in turn defines a ring homomorphism `{{nowrap|''η'' : ''R'' → ''A''}}`{=mediawiki} whose image lies in the center.
If a ring is commutative then it equals its center, so that a commutative *R*-algebra can be defined simply as a commutative ring *A* together with a commutative ring homomorphism `{{nowrap|''η'' : ''R'' → ''A''}}`{=mediawiki}.
The ring homomorphism *η* appearing in the above is often called a structure map. In the commutative case, one can consider the category whose objects are ring homomorphisms `{{nowrap|''R'' → ''A''}}`{=mediawiki} for a fixed *R*, i.e., commutative *R*-algebras, and whose morphisms are ring homomorphisms `{{nowrap|''A'' → ''A''′}}`{=mediawiki} that are under *R*; i.e., `{{nowrap|''R'' → ''A'' → ''A''′}}`{=mediawiki} is `{{nowrap|''R'' → ''A''′}}`{=mediawiki} (i.e., the coslice category of the category of commutative rings under *R*.) The prime spectrum functor Spec then determines an anti-equivalence of this category to the category of affine schemes over Spec *R*.
How to weaken the commutativity assumption is a subject matter of noncommutative algebraic geometry and, more recently, of derived algebraic geometry. See also: *Generic matrix ring*.
## Algebra homomorphisms {#algebra_homomorphisms}
A homomorphism between two *R*-algebras is an *R*-linear ring homomorphism. Explicitly, `{{nowrap|''φ'' : ''A''<sub>1</sub> → ''A''<sub>2</sub>}}`{=mediawiki} is an **associative algebra homomorphism** if
: \\begin{align}
` \varphi(r \cdot x) &= r \cdot \varphi(x) \\`\
` \varphi(x + y) &= \varphi(x) + \varphi(y) \\`\
` \varphi(xy) &= \varphi(x)\varphi(y) \\`\
` \varphi(1) &= 1`
\\end{align}
The class of all *R*-algebras together with algebra homomorphisms between them form a category, sometimes denoted ***R*-Alg**.
The subcategory of commutative *R*-algebras can be characterized as the coslice category *R*/**CRing** where **CRing** is the category of commutative rings.
| 924 |
Associative algebra
| 0 |
2,112 |
# Associative algebra
## Examples
The most basic example is a ring itself; it is an algebra over its center or any subring lying in the center. In particular, any commutative ring is an algebra over any of its subrings. Other examples abound both from algebra and other fields of mathematics.
### Algebra
- Any ring *A* can be considered as a **Z**-algebra. The unique ring homomorphism from **Z** to *A* is determined by the fact that it must send 1 to the identity in *A*. Therefore, rings and **Z**-algebras are equivalent concepts, in the same way that abelian groups and **Z**-modules are equivalent.
- Any ring of characteristic *n* is a (**Z**/*n***Z**)-algebra in the same way.
- Given an *R*-module *M*, the endomorphism ring of *M*, denoted End~*R*~(*M*) is an *R*-algebra by defining `{{nowrap|1=(''r''·''φ'')(''x'') = ''r''·''φ''(''x'')}}`{=mediawiki}.
- Any ring of matrices with coefficients in a commutative ring *R* forms an *R*-algebra under matrix addition and multiplication. This coincides with the previous example when *M* is a finitely-generated, free *R*-module.
- In particular, the square *n*-by-*n* matrices with entries from the field *K* form an associative algebra over *K*.
- The complex numbers form a 2-dimensional commutative algebra over the real numbers.
- The quaternions form a 4-dimensional associative algebra over the reals (but not an algebra over the complex numbers, since the complex numbers are not in the center of the quaternions).
- Every polynomial ring `{{nowrap|''R''[''x''<sub>1</sub>, ..., ''x<sub>n</sub>'']}}`{=mediawiki} is a commutative *R*-algebra. In fact, this is the free commutative *R*-algebra on the set `{{nowrap|{{mset|''x''<sub>1</sub>, ..., ''x<sub>n</sub>''}}}}`{=mediawiki}.
- The free *R*-algebra on a set *E* is an algebra of \"polynomials\" with coefficients in *R* and noncommuting indeterminates taken from the set *E*.
- The tensor algebra of an *R*-module is naturally an associative *R*-algebra. The same is true for quotients such as the exterior and symmetric algebras. Categorically speaking, the functor that maps an *R*-module to its tensor algebra is left adjoint to the functor that sends an *R*-algebra to its underlying *R*-module (forgetting the multiplicative structure).
- Given a module *M* over a commutative ring *R*, the direct sum of modules `{{nowrap|1=''R'' ⊕ ''M''}}`{=mediawiki} has a structure of an *R*-algebra by thinking *M* consists of infinitesimal elements; i.e., the multiplication is given as `{{nowrap|1=(''a'' + ''x'')(''b'' + ''y'') = ''ab'' + ''ay'' + ''bx''}}`{=mediawiki}. The notion is sometimes called the algebra of dual numbers.
- A quasi-free algebra, introduced by Cuntz and Quillen, is a sort of generalization of a free algebra and a semisimple algebra over an algebraically closed field.
### Representation theory {#representation_theory}
- The universal enveloping algebra of a Lie algebra is an associative algebra that can be used to study the given Lie algebra.
- If *G* is a group and *R* is a commutative ring, the set of all functions from *G* to *R* with finite support form an *R*-algebra with the convolution as multiplication. It is called the group algebra of *G*. The construction is the starting point for the application to the study of (discrete) groups.
- If *G* is an algebraic group (e.g., semisimple complex Lie group), then the coordinate ring of *G* is the Hopf algebra *A* corresponding to *G*. Many structures of *G* translate to those of *A*.
- A quiver algebra (or a path algebra) of a directed graph is the free associative algebra over a field generated by the paths in the graph.
### Analysis
- Given any Banach space *X*, the continuous linear operators `{{nowrap|''A'' : ''X'' → ''X''}}`{=mediawiki} form an associative algebra (using composition of operators as multiplication); this is a Banach algebra.
- Given any topological space *X*, the continuous real- or complex-valued functions on *X* form a real or complex associative algebra; here the functions are added and multiplied pointwise.
- The set of semimartingales defined on the filtered probability space `{{nowrap|(Ω, ''F'', (''F''<sub>''t''</sub>)<sub>''t''≥0</sub>, P)}}`{=mediawiki} forms a ring under stochastic integration.
- The Weyl algebra
- An Azumaya algebra
### Geometry and combinatorics {#geometry_and_combinatorics}
- The Clifford algebras, which are useful in geometry and physics.
- Incidence algebras of locally finite partially ordered sets are associative algebras considered in combinatorics.
- The partition algebra and its subalgebras, including the Brauer algebra and the Temperley-Lieb algebra.
- A differential graded algebra is an associative algebra together with a grading and a differential. For example, the de Rham algebra $\Omega(M) = \bigoplus_{p=0}^n \Omega^p(M)$, where $\Omega^p(M)$ consists of differential *p*-forms on a manifold *M*, is a differential graded algebra.
### Mathematical physics {#mathematical_physics}
- A Poisson algebra is a commutative associative algebra over a field together with a structure of a Lie algebra so that the Lie bracket `{{mset|,}}`{=mediawiki} satisfies the Leibniz rule; i.e., `{{nowrap|1={{mset|''fg'', ''h''}} = {{itco|''f''}}{{mset|''g'', ''h''}} + ''g''{{mset|''f'', ''h''}}}}`{=mediawiki}.
- Given a Poisson algebra $\mathfrak a$, consider the vector space $\mathfrak{a}[\![u]\!]$ of formal power series over $\mathfrak{a}$. If $\mathfrak{a}[\![u]\!]$ has a structure of an associative algebra with multiplication $*$ such that, for $f, g \in \mathfrak{a}$,
: $f * g = f g - \frac{1}{2} \{ f, g \} u + \cdots,$
: then $\mathfrak{a}[\![u]\!]$ is called a deformation quantization of $\mathfrak a$.
- A quantized enveloping algebra. The dual of such an algebra turns out to be an associative algebra (see `{{slink||Dual of an associative algebra}}`{=mediawiki}) and is, philosophically speaking, the (quantized) coordinate ring of a quantum group.
- Gerstenhaber algebra
| 890 |
Associative algebra
| 1 |
2,112 |
# Associative algebra
## Constructions
Subalgebras : A subalgebra of an *R*-algebra *A* is a subset of *A* which is both a subring and a submodule of *A*. That is, it must be closed under addition, ring multiplication, scalar multiplication, and it must contain the identity element of *A*.\
Quotient algebras : Let *A* be an *R*-algebra. Any ring-theoretic ideal *I* in *A* is automatically an *R*-module since `{{nowrap|1=''r'' · ''x'' = (''r''1<sub>''A''</sub>)''x''}}`{=mediawiki}. This gives the quotient ring `{{nowrap|''A'' / ''I''}}`{=mediawiki} the structure of an *R*-module and, in fact, an *R*-algebra. It follows that any ring homomorphic image of *A* is also an *R*-algebra.\
Direct products : The direct product of a family of *R*-algebras is the ring-theoretic direct product. This becomes an *R*-algebra with the obvious scalar multiplication.\
Free products: One can form a free product of *R*-algebras in a manner similar to the free product of groups. The free product is the coproduct in the category of *R*-algebras.\
Tensor products : The tensor product of two *R*-algebras is also an *R*-algebra in a natural way. See tensor product of algebras for more details. Given a commutative ring *R* and any ring *A* the tensor product *R* ⊗~**Z**~ *A* can be given the structure of an *R*-algebra by defining `{{nowrap|1=''r'' · (''s'' ⊗ ''a'') = (''rs'' ⊗ ''a'')}}`{=mediawiki}. The functor which sends *A* to `{{nowrap|''R'' ⊗<sub>'''Z'''</sub> ''A''}}`{=mediawiki} is left adjoint to the functor which sends an *R*-algebra to its underlying ring (forgetting the module structure). See also: Change of rings.\
Free algebra : A free algebra is an algebra generated by symbols. If one imposes commutativity; i.e., take the quotient by commutators, then one gets a polynomial algebra.
| 279 |
Associative algebra
| 2 |
2,112 |
# Associative algebra
## Dual of an associative algebra {#dual_of_an_associative_algebra}
Let *A* be an associative algebra over a commutative ring *R*. Since *A* is in particular a module, we can take the dual module *A*^\*^ of *A*. A priori, the dual *A*^\*^ need not have a structure of an associative algebra. However, *A* may come with an extra structure (namely, that of a Hopf algebra) so that the dual is also an associative algebra.
For example, take *A* to be the ring of continuous functions on a compact group *G*. Then, not only *A* is an associative algebra, but it also comes with the co-multiplication `{{nowrap|1=Δ({{itco|''f''}})(''g'', ''h'') = {{itco|''f''}}(''gh'')}}`{=mediawiki} and co-unit `{{nowrap|1=''ε''({{itco|''f''}}) = {{itco|''f''}}(1)}}`{=mediawiki}. The \"co-\" refers to the fact that they satisfy the dual of the usual multiplication and unit in the algebra axiom. Hence, the dual *A*^\*^ is an associative algebra. The co-multiplication and co-unit are also important in order to form a tensor product of representations of associative algebras (see *`{{slink|#Representations}}`{=mediawiki}* below).
## Enveloping algebra {#enveloping_algebra}
Given an associative algebra *A* over a commutative ring *R*, the **enveloping algebra** *A*^e^ of *A* is the algebra `{{nowrap|''A'' ⊗<sub>''R''</sub> ''A''<sup>op</sup>}}`{=mediawiki} or `{{nowrap|''A''<sup>op</sup> ⊗<sub>''R''</sub> ''A''}}`{=mediawiki}, depending on authors.
Note that a bimodule over *A* is exactly a left module over *A*^e^.
## Separable algebra {#separable_algebra}
Let *A* be an algebra over a commutative ring *R*. Then the algebra *A* is a right module over `{{nowrap|1=''A''<sup>e</sup> := ''A''<sup>op</sup> ⊗<sub>''R''</sub> ''A''}}`{=mediawiki} with the action `{{nowrap|1=''x'' ⋅ (''a'' ⊗ ''b'') = ''axb''}}`{=mediawiki}. Then, by definition, *A* is said to separable if the multiplication map `{{nowrap|''A'' ⊗<sub>''R''</sub> ''A'' → ''A'' : ''x'' ⊗ ''y'' ↦ ''xy''}}`{=mediawiki} splits as an *A*^e^-linear map, where `{{nowrap|''A'' ⊗ ''A''}}`{=mediawiki} is an *A*^e^-module by `{{nowrap|1=(''x'' ⊗ ''y'') ⋅ (''a'' ⊗ ''b'') = ''ax'' ⊗ ''yb''}}`{=mediawiki}. Equivalently, *A* is separable if it is a projective module over `{{nowrap|''A''<sup>e</sup>}}`{=mediawiki}; thus, the `{{nowrap|''A''<sup>e</sup>}}`{=mediawiki}-projective dimension of *A*, sometimes called the **bidimension** of *A*, measures the failure of separability.
| 325 |
Associative algebra
| 3 |
2,112 |
# Associative algebra
## Finite-dimensional algebra {#finite_dimensional_algebra}
Let *A* be a finite-dimensional algebra over a field *k*. Then *A* is an Artinian ring.
### Commutative case {#commutative_case}
As *A* is Artinian, if it is commutative, then it is a finite product of Artinian local rings whose residue fields are algebras over the base field *k*. Now, a reduced Artinian local ring is a field and thus the following are equivalent
1. $A$ is separable.
2. $A \otimes \overline{k}$ is reduced, where $\overline{k}$ is some algebraic closure of *k*.
3. $A \otimes \overline{k} = \overline{k}^n$ for some *n*.
4. $\dim_k A$ is the number of $k$-algebra homomorphisms $A \to \overline{k}$.
Let $\Gamma = \operatorname{Gal}(k_s/k) = \varprojlim \operatorname{Gal}(k'/k)$, the profinite group of finite Galois extensions of *k*. Then $A \mapsto X_A = \{ k\text{-algebra homomorphisms } A \to k_s \}$ is an anti-equivalence of the category of finite-dimensional separable *k*-algebras to the category of finite sets with continuous $\Gamma$-actions.
### Noncommutative case {#noncommutative_case}
Since a simple Artinian ring is a (full) matrix ring over a division ring, if *A* is a simple algebra, then *A* is a (full) matrix algebra over a division algebra *D* over *k*; i.e., `{{nowrap|1=''A'' = M<sub>''n''</sub>(''D'')}}`{=mediawiki}. More generally, if *A* is a semisimple algebra, then it is a finite product of matrix algebras (over various division *k*-algebras), the fact known as the Artin--Wedderburn theorem.
The fact that *A* is Artinian simplifies the notion of a Jacobson radical; for an Artinian ring, the Jacobson radical of *A* is the intersection of all (two-sided) maximal ideals (in contrast, in general, a Jacobson radical is the intersection of all left maximal ideals or the intersection of all right maximal ideals.)
The **Wedderburn principal theorem** states: for a finite-dimensional algebra *A* with a nilpotent ideal *I*, if the projective dimension of `{{nowrap|''A'' / ''I''}}`{=mediawiki} as a module over the enveloping algebra `{{nowrap|(''A'' / ''I'')<sup>e</sup>}}`{=mediawiki} is at most one, then the natural surjection `{{nowrap|''p'' : ''A'' → ''A'' / ''I''}}`{=mediawiki} splits; i.e., *A* contains a subalgebra *B* such that `{{nowrap|''p''{{!}}`{=mediawiki}~*B*~ : *B* `{{overset|lh=0.5|~|→}}`{=mediawiki} *A* / *I*}} is an isomorphism. Taking *I* to be the Jacobson radical, the theorem says in particular that the Jacobson radical is complemented by a semisimple algebra. The theorem is an analog of Levi\'s theorem for Lie algebras.
## Lattices and orders {#lattices_and_orders}
Let *R* be a Noetherian integral domain with field of fractions *K* (for example, they can be **Z**, **Q**). A *lattice* *L* in a finite-dimensional *K*-vector space *V* is a finitely generated *R*-submodule of *V* that spans *V*; in other words, `{{nowrap|1=''L'' ⊗<sub>''R''</sub> ''K'' = ''V''}}`{=mediawiki}.
Let *A*~*K*~ be a finite-dimensional *K*-algebra. An *order* in *A*~*K*~ is an *R*-subalgebra that is a lattice. In general, there are a lot fewer orders than lattices; e.g., `{{sfrac|1|2}}`{=mediawiki}**Z** is a lattice in **Q** but not an order (since it is not an algebra).
A *maximal order* is an order that is maximal among all the orders.
## Related concepts {#related_concepts}
### Coalgebras
An associative algebra over *K* is given by a *K*-vector space *A* endowed with a bilinear map `{{nowrap|''A'' × ''A'' → ''A''}}`{=mediawiki} having two inputs (multiplicator and multiplicand) and one output (product), as well as a morphism `{{nowrap|''K'' → ''A''}}`{=mediawiki} identifying the scalar multiples of the multiplicative identity. If the bilinear map `{{nowrap|''A'' × ''A'' → ''A''}}`{=mediawiki} is reinterpreted as a linear map (i.e., morphism in the category of *K*-vector spaces) `{{nowrap|''A'' ⊗ ''A'' → ''A''}}`{=mediawiki} (by the universal property of the tensor product), then we can view an associative algebra over *K* as a *K*-vector space *A* endowed with two morphisms (one of the form `{{nowrap|''A'' ⊗ ''A'' → ''A''}}`{=mediawiki} and one of the form `{{nowrap|''K'' → ''A''}}`{=mediawiki}) satisfying certain conditions that boil down to the algebra axioms. These two morphisms can be dualized using categorial duality by reversing all arrows in the commutative diagrams that describe the algebra axioms; this defines the structure of a coalgebra.
There is also an abstract notion of *F*-coalgebra, where *F* is a functor. This is vaguely related to the notion of coalgebra discussed above.
| 676 |
Associative algebra
| 4 |
2,112 |
# Associative algebra
## Representations
A representation of an algebra *A* is an algebra homomorphism `{{nowrap|''ρ'' : ''A'' → End(''V'')}}`{=mediawiki} from *A* to the endomorphism algebra of some vector space (or module) *V*. The property of *ρ* being an algebra homomorphism means that *ρ* preserves the multiplicative operation (that is, `{{nowrap|1=''ρ''(''xy'') = ''ρ''(''x'')''ρ''(''y'')}}`{=mediawiki} for all *x* and *y* in *A*), and that *ρ* sends the unit of *A* to the unit of End(*V*) (that is, to the identity endomorphism of *V*).
If *A* and *B* are two algebras, and `{{nowrap|''ρ'' : ''A'' → End(''V'')}}`{=mediawiki} and `{{nowrap|''τ'' : ''B'' → End(''W'')}}`{=mediawiki} are two representations, then there is a (canonical) representation `{{nowrap|''A'' ⊗ ''B'' → End(''V'' ⊗ ''W'')}}`{=mediawiki} of the tensor product algebra `{{nowrap|''A'' ⊗ ''B''}}`{=mediawiki} on the vector space `{{nowrap|''V'' ⊗ ''W''}}`{=mediawiki}. However, there is no natural way of defining a tensor product of two representations of a single associative algebra in such a way that the result is still a representation of that same algebra (not of its tensor product with itself), without somehow imposing additional conditions. Here, by *tensor product of representations*, the usual meaning is intended: the result should be a linear representation of the same algebra on the product vector space. Imposing such additional structure typically leads to the idea of a Hopf algebra or a Lie algebra, as demonstrated below.
### Motivation for a Hopf algebra {#motivation_for_a_hopf_algebra}
Consider, for example, two representations `{{nowrap|''σ'' : ''A'' → End(''V'')}}`{=mediawiki} and `{{nowrap|''τ'' : ''A'' → End(''W'')}}`{=mediawiki}. One might try to form a tensor product representation `{{nowrap|''ρ'' : ''x'' ↦ ''σ''(''x'') ⊗ ''τ''(''x'')}}`{=mediawiki} according to how it acts on the product vector space, so that
: $\rho(x)(v \otimes w) = (\sigma(x)(v)) \otimes (\tau(x)(w)).$
However, such a map would not be linear, since one would have
: $\rho(kx) = \sigma(kx) \otimes \tau(kx) = k\sigma(x) \otimes k\tau(x) = k^2 (\sigma(x) \otimes \tau(x)) = k^2 \rho(x)$
for `{{nowrap|''k'' ∈ ''K''}}`{=mediawiki}. One can rescue this attempt and restore linearity by imposing additional structure, by defining an algebra homomorphism `{{nowrap|Δ : ''A'' → ''A'' ⊗ ''A''}}`{=mediawiki}, and defining the tensor product representation as
: $\rho = (\sigma\otimes \tau) \circ \Delta.$
Such a homomorphism Δ is called a comultiplication if it satisfies certain axioms. The resulting structure is called a bialgebra. To be consistent with the definitions of the associative algebra, the coalgebra must be co-associative, and, if the algebra is unital, then the co-algebra must be co-unital as well. A Hopf algebra is a bialgebra with an additional piece of structure (the so-called antipode), which allows not only to define the tensor product of two representations, but also the Hom module of two representations (again, similarly to how it is done in the representation theory of groups).
### Motivation for a Lie algebra {#motivation_for_a_lie_algebra}
One can try to be more clever in defining a tensor product. Consider, for example,
: $x \mapsto \rho (x) = \sigma(x) \otimes \mbox{Id}_W + \mbox{Id}_V \otimes \tau(x)$
so that the action on the tensor product space is given by
: $\rho(x) (v \otimes w) = (\sigma(x) v)\otimes w + v \otimes (\tau(x) w)$.
This map is clearly linear in *x*, and so it does not have the problem of the earlier definition. However, it fails to preserve multiplication:
: $\rho(xy) = \sigma(x) \sigma(y) \otimes \mbox{Id}_W + \mbox{Id}_V \otimes \tau(x) \tau(y)$.
But, in general, this does not equal
: $\rho(x)\rho(y) = \sigma(x) \sigma(y) \otimes \mbox{Id}_W + \sigma(x) \otimes \tau(y) + \sigma(y) \otimes \tau(x) + \mbox{Id}_V \otimes \tau(x) \tau(y)$.
This shows that this definition of a tensor product is too naive; the obvious fix is to define it such that it is antisymmetric, so that the middle two terms cancel. This leads to the concept of a Lie algebra.
| 617 |
Associative algebra
| 5 |
2,112 |
# Associative algebra
## Non-unital algebras {#non_unital_algebras}
Some authors use the term \"associative algebra\" to refer to structures which do not necessarily have a multiplicative identity, and hence consider homomorphisms which are not necessarily unital.
One example of a non-unital associative algebra is given by the set of all functions `{{nowrap|''f'' : '''R''' → '''R'''}}`{=mediawiki} whose limit as *x* nears infinity is zero.
Another example is the vector space of continuous periodic functions, together with the convolution product
| 78 |
Associative algebra
| 6 |
2,113 |
# Axiom of regularity
In mathematics, the **axiom of regularity** (also known as the **axiom of foundation**) is an axiom of Zermelo--Fraenkel set theory that states that every non-empty set *A* contains an element that is disjoint from *A*. In first-order logic, the axiom reads:
$\forall x\,(x \neq \varnothing \rightarrow (\exists y \in x) (y \cap x = \varnothing)).$
The axiom of regularity together with the axiom of pairing implies that no set is an element of itself, and that there is no infinite sequence $(a_n)$ such that $a_{i+1}$ is an element of $a_i$ for all $i$. With the axiom of dependent choice (which is a weakened form of the axiom of choice), this result can be reversed: if there are no such infinite sequences, then the axiom of regularity is true. Hence, in this context the axiom of regularity is equivalent to the sentence that there are no downward infinite membership chains.
The axiom was originally formulated by von Neumann; it was adopted in a formulation closer to the one found in contemporary textbooks by Zermelo. Virtually all results in the branches of mathematics based on set theory hold even in the absence of regularity. However, regularity makes some properties of ordinals easier to prove; and it not only allows induction to be done on well-ordered sets but also on proper classes that are well-founded relational structures such as the lexicographical ordering on $\{ (n, \alpha) \mid n \in \omega \land \alpha \text{ is an ordinal } \} \,.$
Given the other axioms of Zermelo--Fraenkel set theory, the axiom of regularity is equivalent to the axiom of induction. The axiom of induction tends to be used in place of the axiom of regularity in intuitionistic theories (ones that do not accept the law of the excluded middle), where the two axioms are not equivalent.
In addition to omitting the axiom of regularity, non-standard set theories have indeed postulated the existence of sets that are elements of themselves.
| 328 |
Axiom of regularity
| 0 |
2,113 |
# Axiom of regularity
## Elementary implications of regularity {#elementary_implications_of_regularity}
### No set is an element of itself {#no_set_is_an_element_of_itself}
Let $A$ be a set, and apply the axiom of regularity to $\{A\}$, which is a set by the axiom of pairing. By this axiom, there must be an element of $\{A\}$ which is disjoint from $\{A\}$. Since the only element of $\{A\}$ is $A$, it must be that $A$ is disjoint from $\{A\}$. So, since $A \cap \{A\} = \varnothing$, we cannot have $A$ an element of $A$ (by the definition of disjointness).
### No infinite descending sequence of sets exists {#no_infinite_descending_sequence_of_sets_exists}
Suppose, to the contrary, that there is a function, *f*, on the natural numbers with *f*(*n*+1) an element of *f*(*n*) for each *n*. Define *S* = {*f*(*n*): *n* a natural number}, the range of *f*, which can be seen to be a set from the axiom schema of replacement. Applying the axiom of regularity to *S*, let *B* be an element of *S* which is disjoint from *S*. By the definition of *S*, *B* must be *f*(*k*) for some natural number *k*. However, we are given that *f*(*k*) contains *f*(*k*+1) which is also an element of *S*. So *f*(*k*+1) is in the intersection of *f*(*k*) and *S*. This contradicts the fact that they are disjoint sets. Since our supposition led to a contradiction, there must not be any such function, *f*.
The nonexistence of a set containing itself can be seen as a special case where the sequence is infinite and constant.
Notice that this argument only applies to functions *f* that can be represented as sets as opposed to undefinable classes. The hereditarily finite sets, *V*~ω~, satisfy the axiom of regularity (and all other axioms of ZFC except the axiom of infinity). So if one forms a non-trivial ultrapower of V~ω~, then it will also satisfy the axiom of regularity. The resulting model will contain elements, called non-standard natural numbers, that satisfy the definition of natural numbers in that model but are not really natural numbers.`{{dubious|date=February 2023|reason=They satisfy the first-order Peano axioms, so it seems dubious to claim that they are not actually natural numbers. They presumably do not satisfy the second-order Peano axioms with respect to the subset relation of the "ambient" set theory inside of which the model is constructed. But don't they actually satisfy the second-order Peano axioms with respect to the internal subset relation of the model?}}`{=mediawiki} They are \"fake\" natural numbers which are \"larger\" than any actual natural number. This model will contain infinite descending sequences of elements.`{{clarification needed|date=February 2023|reason=Is the set membership relation in this infinite descending chain the "internal" set membership relation of the model? (I.e. the model's interpretation of the set membership relation?) Or is what follows referring to the set membership relation of the "ambient" set theory in which the model is constructed? Presumably it can't be the latter, because the fact that the latter has a von Neumann cumulative hierarchy, e.g. V_omega, seems to presuppose that it satisfies regularity, and thus otherwise this section would be describing a contradiction. If so, then this section ideally would clarify that what follows refers to the model's interpretation of the set membership relation, and that this is necessarily distinct from (in particular not the restriction of) the ambient set theory's set membership relation.}}`{=mediawiki} For example, suppose *n* is a non-standard natural number, then $(n-1) \in n$ and $(n-2) \in (n-1)$, and so on. For any actual natural number *k*, $(n-k-1) \in (n-k)$. This is an unending descending sequence of elements. But this sequence is not definable in the model and thus not a set. So no contradiction to regularity can be proved.
### Simpler set-theoretic definition of the ordered pair {#simpler_set_theoretic_definition_of_the_ordered_pair}
The axiom of regularity enables defining the ordered pair (*a*,*b*) as {*a*,{*a*,*b*}}; see ordered pair for specifics. This definition eliminates one pair of braces from the canonical Kuratowski definition (*a*,*b*) = {{*a*},{*a*,*b*}}.
### Every set has an ordinal rank {#every_set_has_an_ordinal_rank}
This was actually the original form of the axiom in von Neumann\'s axiomatization.
Suppose *x* is any set. Let *t* be the transitive closure of {*x*}. Let *u* be the subset of *t* consisting of unranked sets. If *u* is empty, then *x* is ranked and we are done. Otherwise, apply the axiom of regularity to *u* to get an element *w* of *u* which is disjoint from *u*. Since *w* is in *u*, *w* is unranked. *w* is a subset of *t* by the definition of transitive closure. Since *w* is disjoint from *u*, every element of *w* is ranked. Applying the axioms of replacement and union to combine the ranks of the elements of *w*, we get an ordinal rank for *w*, to wit $\textstyle \operatorname{rank} (w) = \cup \{ \operatorname{rank} (z) + 1 \mid z \in w \}$. This contradicts the conclusion that *w* is unranked. So the assumption that *u* was non-empty must be false and *x* must have rank.
### For every two sets, only one can be an element of the other {#for_every_two_sets_only_one_can_be_an_element_of_the_other}
Let *X* and *Y* be sets. Then apply the axiom of regularity to the set {*X*,*Y*} (which exists by the axiom of pairing). We see there must be an element of {*X*,*Y*} which is also disjoint from it. It must be either *X* or *Y*. By the definition of disjoint then, we must have either *Y* is not an element of *X* or vice versa.
## The axiom of dependent choice and no infinite descending sequence of sets implies regularity {#the_axiom_of_dependent_choice_and_no_infinite_descending_sequence_of_sets_implies_regularity}
Let the non-empty set *S* be a counter-example to the axiom of regularity; that is, every element of *S* has a non-empty intersection with *S*. We define a binary relation *R* on *S* by $aRb :\Leftrightarrow b \in S \cap a$, which is entire by assumption. Thus, by the axiom of dependent choice, there is some sequence (*a~n~*) in *S* satisfying *a~n~Ra~n+1~* for all *n* in **N**. As this is an infinite descending chain, we arrive at a contradiction and so, no such *S* exists.
| 1,006 |
Axiom of regularity
| 1 |
2,113 |
# Axiom of regularity
## Regularity and the rest of ZF(C) axioms {#regularity_and_the_rest_of_zfc_axioms}
Regularity was shown to be relatively consistent with the rest of ZF by Skolem and von Neumann, meaning that if ZF without regularity is consistent, then ZF (with regularity) is also consistent.
The axiom of regularity was also shown to be independent from the other axioms of ZFC, assuming they are consistent. The result was announced by Paul Bernays in 1941, although he did not publish a proof until 1954. The proof involves (and led to the study of) Rieger-Bernays permutation models (or method), which were used for other proofs of independence for non-well-founded systems.
## Regularity in ordinary mathematics {#regularity_in_ordinary_mathematics}
The axiom of regularity is rarely useful outside of set theory; A. A. Fraenkel, Y. Bar-Hillel and A. Levy noted that "its omission will not incapacitate any field of mathematics". Its inclusion, therefore, can be considered as chiefly a clarification of what one means by "set", as elaborated on by the Mostowski collapse lemma (which provides the converse: that not only is membership on every set a well-founded and extensional relation, but that any such relation admits a corresponding set). If one performs mathematics in a more structural setting, for example by using a type theory or structural set theory like ETCS, the axiom is not used at all, since it is not needed to prove that **Set**, the category of sets, forms an elementary topos.
However, it does have practical uses, especially in the absence of the axiom of choice. One application is Scott\'s trick for constructing equivalence classes of a relation defined on proper classes, as an alternative to postulating a Grothendieck universe; it may also be used as an alternative to choice in the proof of Frucht\'s theorem for infinite groups.
| 298 |
Axiom of regularity
| 2 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.