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1212.5776
Mohammed El-Dosuky
M. A. El-Dosuky, M. Z. Rashad, T. T. Hamza and A.H. EL-Bassiouny
Improving problem solving by exploiting the concept of symmetry
null
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We investigate the concept of symmetry and its role in problem solving. This paper first defines precisely the elements that constitute a "problem" and its "solution," and gives several examples to illustrate these definitions. Given precise definitions of problems, it is relatively straightforward to construct a search process for finding solutions. Finally this paper attempts to exploit the concept of symmetry in improving problem solving.
[ { "version": "v1", "created": "Sun, 23 Dec 2012 09:18:59 GMT" }, { "version": "v2", "created": "Mon, 4 Mar 2013 23:26:24 GMT" } ]
1,362,528,000,000
[ [ "El-Dosuky", "M. A.", "" ], [ "Rashad", "M. Z.", "" ], [ "Hamza", "T. T.", "" ], [ "EL-Bassiouny", "A. H.", "" ] ]
1212.6207
Kirill Sorudeykin Mr
Kirill A. Sorudeykin
Irrespective Priority-Based Regular Properties of High-Intensity Virtual Environments
4 pages, 2 figures; ISBN: 978-1-4673-2984-2
20th Telecommunications Forum TELFOR 2012, 2012, pp. 510-513
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We have a lot of relation to the encoding and the Theory of Information, when considering thinking. This is a natural process and, at once, the complex thing we investigate. This always was a challenge - to understand how our mind works, and we are trying to find some universal models for this. A lot of ways have been considered so far, but we are looking for Something, we seek for approaches. And the goal is to find a consistent, noncontradictory view, which should at once be enough flexible in any dimensions to allow to represent various kinds of processes and environments, matters of different nature and diverse objects. Developing of such a model is the destination of this article.
[ { "version": "v1", "created": "Fri, 21 Dec 2012 08:43:22 GMT" } ]
1,356,566,400,000
[ [ "Sorudeykin", "Kirill A.", "" ] ]
1212.6521
Jan Koutn\'ik
Jan Koutn\'ik, Juergen Schmidhuber, Faustino Gomez
A Frequency-Domain Encoding for Neuroevolution
null
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Neuroevolution has yet to scale up to complex reinforcement learning tasks that require large networks. Networks with many inputs (e.g. raw video) imply a very high dimensional search space if encoded directly. Indirect methods use a more compact genotype representation that is transformed into networks of potentially arbitrary size. In this paper, we present an indirect method where networks are encoded by a set of Fourier coefficients which are transformed into network weight matrices via an inverse Fourier-type transform. Because there often exist network solutions whose weight matrices contain regularity (i.e. adjacent weights are correlated), the number of coefficients required to represent these networks in the frequency domain is much smaller than the number of weights (in the same way that natural images can be compressed by ignore high-frequency components). This "compressed" encoding is compared to the direct approach where search is conducted in the weight space on the high-dimensional octopus arm task. The results show that representing networks in the frequency domain can reduce the search-space dimensionality by as much as two orders of magnitude, both accelerating convergence and yielding more general solutions.
[ { "version": "v1", "created": "Fri, 28 Dec 2012 14:23:02 GMT" } ]
1,356,998,400,000
[ [ "Koutník", "Jan", "" ], [ "Schmidhuber", "Juergen", "" ], [ "Gomez", "Faustino", "" ] ]
1212.6550
Andre Martins
Andre F. T. Martins, Mario A. T. Figueiredo, Pedro M. Q. Aguiar, Noah A. Smith, Eric P. Xing
Alternating Directions Dual Decomposition
null
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose AD3, a new algorithm for approximate maximum a posteriori (MAP) inference on factor graphs based on the alternating directions method of multipliers. Like dual decomposition algorithms, AD3 uses worker nodes to iteratively solve local subproblems and a controller node to combine these local solutions into a global update. The key characteristic of AD3 is that each local subproblem has a quadratic regularizer, leading to a faster consensus than subgradient-based dual decomposition, both theoretically and in practice. We provide closed-form solutions for these AD3 subproblems for binary pairwise factors and factors imposing first-order logic constraints. For arbitrary factors (large or combinatorial), we introduce an active set method which requires only an oracle for computing a local MAP configuration, making AD3 applicable to a wide range of problems. Experiments on synthetic and realworld problems show that AD3 compares favorably with the state-of-the-art.
[ { "version": "v1", "created": "Fri, 28 Dec 2012 18:38:57 GMT" } ]
1,356,998,400,000
[ [ "Martins", "Andre F. T.", "" ], [ "Figueiredo", "Mario A. T.", "" ], [ "Aguiar", "Pedro M. Q.", "" ], [ "Smith", "Noah A.", "" ], [ "Xing", "Eric P.", "" ] ]
1301.0216
Jan Hrncir
Jan Hrn\v{c}\'i\v{r} and Michael Rovatsos
Applying Strategic Multiagent Planning to Real-World Travel Sharing Problems
7th International Workshop on Agents in Traffic and Transportation, AAMAS, 2012
null
null
null
cs.AI
http://creativecommons.org/licenses/by/3.0/
Travel sharing, i.e., the problem of finding parts of routes which can be shared by several travellers with different points of departure and destinations, is a complex multiagent problem that requires taking into account individual agents' preferences to come up with mutually acceptable joint plans. In this paper, we apply state-of-the-art planning techniques to real-world public transportation data to evaluate the feasibility of multiagent planning techniques in this domain. The potential application value of improving travel sharing technology has great application value due to its ability to reduce the environmental impact of travelling while providing benefits to travellers at the same time. We propose a three-phase algorithm that utilises performant single-agent planners to find individual plans in a simplified domain first, then merges them using a best-response planner which ensures resulting solutions are individually rational, and then maps the resulting plan onto the full temporal planning domain to schedule actual journeys. The evaluation of our algorithm on real-world, multi-modal public transportation data for the United Kingdom shows linear scalability both in the scenario size and in the number of agents, where trade-offs have to be made between total cost improvement, the percentage of feasible timetables identified for journeys, and the prolongation of these journeys. Our system constitutes the first implementation of strategic multiagent planning algorithms in large-scale domains and provides insights into the engineering process of translating general domain-independent multiagent planning algorithms to real-world applications.
[ { "version": "v1", "created": "Wed, 2 Jan 2013 12:06:59 GMT" } ]
1,357,171,200,000
[ [ "Hrnčíř", "Jan", "" ], [ "Rovatsos", "Michael", "" ] ]
1301.0552
Ionut Aron
Ionut Aron, Pascal Van Hentenryck
A constraint satisfaction approach to the robust spanning tree problem with interval data
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-18-25
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Robust optimization is one of the fundamental approaches to deal with uncertainty in combinatorial optimization. This paper considers the robust spanning tree problem with interval data, which arises in a variety of telecommunication applications. It proposes a constraint satisfaction approach using a combinatorial lower bound, a pruning component that removes infeasible and suboptimal edges, as well as a search strategy exploring the most uncertain edges first. The resulting algorithm is shown to produce very dramatic improvements over the mathematical programming approach of Yaman et al. and to enlarge considerably the class of problems amenable to effective solutions
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:55:09 GMT" } ]
1,357,516,800,000
[ [ "Aron", "Ionut", "" ], [ "Van Hentenryck", "Pascal", "" ] ]
1301.0553
Vincent Auvray
Vincent Auvray, Louis Wehenkel
On the Construction of the Inclusion Boundary Neighbourhood for Markov Equivalence Classes of Bayesian Network Structures
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-26-35
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The problem of learning Markov equivalence classes of Bayesian network structures may be solved by searching for the maximum of a scoring metric in a space of these classes. This paper deals with the definition and analysis of one such search space. We use a theoretically motivated neighbourhood, the inclusion boundary, and represent equivalence classes by essential graphs. We show that this search space is connected and that the score of the neighbours can be evaluated incrementally. We devise a practical way of building this neighbourhood for an essential graph that is purely graphical and does not explicitely refer to the underlying independences. We find that its size can be intractable, depending on the complexity of the essential graph of the equivalence class. The emphasis is put on the potential use of this space with greedy hill -climbing search
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:55:13 GMT" } ]
1,357,516,800,000
[ [ "Auvray", "Vincent", "" ], [ "Wehenkel", "Louis", "" ] ]
1301.0555
Salem Benferhat
Salem Benferhat, Didier Dubois, Souhila Kaci, Henri Prade
Bipolar Possibilistic Representations
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-45-52
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Recently, it has been emphasized that the possibility theory framework allows us to distinguish between i) what is possible because it is not ruled out by the available knowledge, and ii) what is possible for sure. This distinction may be useful when representing knowledge, for modelling values which are not impossible because they are consistent with the available knowledge on the one hand, and values guaranteed to be possible because reported from observations on the other hand. It is also of interest when expressing preferences, to point out values which are positively desired among those which are not rejected. This distinction can be encoded by two types of constraints expressed in terms of necessity measures and in terms of guaranteed possibility functions, which induce a pair of possibility distributions at the semantic level. A consistency condition should ensure that what is claimed to be guaranteed as possible is indeed not impossible. The present paper investigates the representation of this bipolar view, including the case when it is stated by means of conditional measures, or by means of comparative context-dependent constraints. The interest of this bipolar framework, which has been recently stressed for expressing preferences, is also pointed out in the representation of diagnostic knowledge.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:55:21 GMT" } ]
1,357,516,800,000
[ [ "Benferhat", "Salem", "" ], [ "Dubois", "Didier", "" ], [ "Kaci", "Souhila", "" ], [ "Prade", "Henri", "" ] ]
1301.0557
Blai Bonet
Blai Bonet, Judea Pearl
Qualitative MDPs and POMDPs: An Order-Of-Magnitude Approximation
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-61-68
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We develop a qualitative theory of Markov Decision Processes (MDPs) and Partially Observable MDPs that can be used to model sequential decision making tasks when only qualitative information is available. Our approach is based upon an order-of-magnitude approximation of both probabilities and utilities, similar to epsilon-semantics. The result is a qualitative theory that has close ties with the standard maximum-expected-utility theory and is amenable to general planning techniques.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:55:30 GMT" } ]
1,357,516,800,000
[ [ "Bonet", "Blai", "" ], [ "Pearl", "Judea", "" ] ]
1301.0558
Ronen I. Brafman
Ronen I. Brafman, Carmel Domshlak
Introducing Variable Importance Tradeoffs into CP-Nets
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-69-76
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The ability to make decisions and to assess potential courses of action is a corner-stone of many AI applications, and usually this requires explicit information about the decision-maker s preferences. IN many applications, preference elicitation IS a serious bottleneck.The USER either does NOT have the time, the knowledge, OR the expert support required TO specify complex multi - attribute utility functions. IN such cases, a method that IS based ON intuitive, yet expressive, preference statements IS required. IN this paper we suggest the USE OF TCP - nets, an enhancement OF CP - nets, AS a tool FOR representing, AND reasoning about qualitative preference statements.We present AND motivate this framework, define its semantics, AND show how it can be used TO perform constrained optimization.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:55:33 GMT" } ]
1,357,516,800,000
[ [ "Brafman", "Ronen I.", "" ], [ "Domshlak", "Carmel", "" ] ]
1301.0559
John Bresina
John Bresina, Richard Dearden, Nicolas Meuleau, Sailesh Ramkrishnan, David Smith, Richard Washington
Planning under Continuous Time and Resource Uncertainty: A Challenge for AI
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-77-84
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We outline a class of problems, typical of Mars rover operations, that are problematic for current methods of planning under uncertainty. The existing methods fail because they suffer from one or more of the following limitations: 1) they rely on very simple models of actions and time, 2) they assume that uncertainty is manifested in discrete action outcomes, 3) they are only practical for very small problems. For many real world problems, these assumptions fail to hold. In particular, when planning the activities for a Mars rover, none of the above assumptions is valid: 1) actions can be concurrent and have differing durations, 2) there is uncertainty concerning action durations and consumption of continuous resources like power, and 3) typical daily plans involve on the order of a hundred actions. This class of problems may be of particular interest to the UAI community because both classical and decision-theoretic planning techniques may be useful in solving it. We describe the rover problem, discuss previous work on planning under uncertainty, and present a detailed, but very small, example illustrating some of the difficulties of finding good plans.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:55:37 GMT" } ]
1,357,516,800,000
[ [ "Bresina", "John", "" ], [ "Dearden", "Richard", "" ], [ "Meuleau", "Nicolas", "" ], [ "Ramkrishnan", "Sailesh", "" ], [ "Smith", "David", "" ], [ "Washington", "Richard", "" ] ]
1301.0560
Carlos Brito
Carlos Brito, Judea Pearl
Generalized Instrumental Variables
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-85-93
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper concerns the assessment of direct causal effects from a combination of: (i) non-experimental data, and (ii) qualitative domain knowledge. Domain knowledge is encoded in the form of a directed acyclic graph (DAG), in which all interactions are assumed linear, and some variables are presumed to be unobserved. We provide a generalization of the well-known method of Instrumental Variables, which allows its application to models with few conditional independeces.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:55:41 GMT" } ]
1,357,516,800,000
[ [ "Brito", "Carlos", "" ], [ "Pearl", "Judea", "" ] ]
1301.0561
David Maxwell Chickering
David Maxwell Chickering, Christopher Meek
Finding Optimal Bayesian Networks
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-94-102
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we derive optimality results for greedy Bayesian-network search algorithms that perform single-edge modifications at each step and use asymptotically consistent scoring criteria. Our results extend those of Meek (1997) and Chickering (2002), who demonstrate that in the limit of large datasets, if the generative distribution is perfect with respect to a DAG defined over the observable variables, such search algorithms will identify this optimal (i.e. generative) DAG model. We relax their assumption about the generative distribution, and assume only that this distribution satisfies the {em composition property} over the observable variables, which is a more realistic assumption for real domains. Under this assumption, we guarantee that the search algorithms identify an {em inclusion-optimal} model; that is, a model that (1) contains the generative distribution and (2) has no sub-model that contains this distribution. In addition, we show that the composition property is guaranteed to hold whenever the dependence relationships in the generative distribution can be characterized by paths between singleton elements in some generative graphical model (e.g. a DAG, a chain graph, or a Markov network) even when the generative model includes unobserved variables, and even when the observed data is subject to selection bias.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:55:46 GMT" } ]
1,357,516,800,000
[ [ "Chickering", "David Maxwell", "" ], [ "Meek", "Christopher", "" ] ]
1301.0564
Rina Dechter
Rina Dechter, Kalev Kask, Robert Mateescu
Iterative Join-Graph Propagation
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-128-136
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The paper presents an iterative version of join-tree clustering that applies the message passing of join-tree clustering algorithm to join-graphs rather than to join-trees, iteratively. It is inspired by the success of Pearl's belief propagation algorithm as an iterative approximation scheme on one hand, and by a recently introduced mini-clustering i. success as an anytime approximation method, on the other. The proposed Iterative Join-graph Propagation IJGP belongs to the class of generalized belief propagation methods, recently proposed using analogy with algorithms in statistical physics. Empirical evaluation of this approach on a number of problem classes demonstrates that even the most time-efficient variant is almost always superior to IBP and MC i, and is sometimes more accurate by as much as several orders of magnitude.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:55:58 GMT" } ]
1,357,516,800,000
[ [ "Dechter", "Rina", "" ], [ "Kask", "Kalev", "" ], [ "Mateescu", "Robert", "" ] ]
1301.0566
Thomas Eiter
Thomas Eiter, Thomas Lukasiewicz
Causes and Explanations in the Structural-Model Approach: Tractable Cases
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-146-153
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we continue our research on the algorithmic aspects of Halpern and Pearl's causes and explanations in the structural-model approach. To this end, we present new characterizations of weak causes for certain classes of causal models, which show that under suitable restrictions deciding causes and explanations is tractable. To our knowledge, these are the first explicit tractability results for the structural-model approach.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:56:06 GMT" } ]
1,357,516,800,000
[ [ "Eiter", "Thomas", "" ], [ "Lukasiewicz", "Thomas", "" ] ]
1301.0568
Dan Geiger
Dan Geiger, Christopher Meek, Bernd Sturmfels
Factorization of Discrete Probability Distributions
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-162-169
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We formulate necessary and sufficient conditions for an arbitrary discrete probability distribution to factor according to an undirected graphical model, or a log-linear model, or other more general exponential models. This result generalizes the well known Hammersley-Clifford Theorem.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:56:14 GMT" } ]
1,357,516,800,000
[ [ "Geiger", "Dan", "" ], [ "Meek", "Christopher", "" ], [ "Sturmfels", "Bernd", "" ] ]
1301.0569
Phan H. Giang
Phan H. Giang, Prakash P. Shenoy
Statistical Decisions Using Likelihood Information Without Prior Probabilities
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-170-178
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper presents a decision-theoretic approach to statistical inference that satisfies the likelihood principle (LP) without using prior information. Unlike the Bayesian approach, which also satisfies LP, we do not assume knowledge of the prior distribution of the unknown parameter. With respect to information that can be obtained from an experiment, our solution is more efficient than Wald's minimax solution.However, with respect to information assumed to be known before the experiment, our solution demands less input than the Bayesian solution.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:56:18 GMT" } ]
1,357,516,800,000
[ [ "Giang", "Phan H.", "" ], [ "Shenoy", "Prakash P.", "" ] ]
1301.0571
Carlos E. Guestrin
Carlos E. Guestrin, Geoffrey Gordon
Distributed Planning in Hierarchical Factored MDPs
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-197-206
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present a principled and efficient planning algorithm for collaborative multiagent dynamical systems. All computation, during both the planning and the execution phases, is distributed among the agents; each agent only needs to model and plan for a small part of the system. Each of these local subsystems is small, but once they are combined they can represent an exponentially larger problem. The subsystems are connected through a subsystem hierarchy. Coordination and communication between the agents is not imposed, but derived directly from the structure of this hierarchy. A globally consistent plan is achieved by a message passing algorithm, where messages correspond to natural local reward functions and are computed by local linear programs; another message passing algorithm allows us to execute the resulting policy. When two portions of the hierarchy share the same structure, our algorithm can reuse plans and messages to speed up computation.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:56:27 GMT" } ]
1,357,516,800,000
[ [ "Guestrin", "Carlos E.", "" ], [ "Gordon", "Geoffrey", "" ] ]
1301.0572
Tom Heskes
Tom Heskes, Onno Zoeter
Expectation Propogation for approximate inference in dynamic Bayesian networks
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-216-223
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We describe expectation propagation for approximate inference in dynamic Bayesian networks as a natural extension of Pearl s exact belief propagation.Expectation propagation IS a greedy algorithm, converges IN many practical cases, but NOT always.We derive a DOUBLE - loop algorithm, guaranteed TO converge TO a local minimum OF a Bethe free energy.Furthermore, we show that stable fixed points OF (damped) expectation propagation correspond TO local minima OF this free energy, but that the converse need NOT be the CASE .We illustrate the algorithms BY applying them TO switching linear dynamical systems AND discuss implications FOR approximate inference IN general Bayesian networks.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:56:30 GMT" } ]
1,357,516,800,000
[ [ "Heskes", "Tom", "" ], [ "Zoeter", "Onno", "" ] ]
1301.0574
Finn Verner Jensen
Finn Verner Jensen, Marta Vomlelova
Unconstrained Influence Diagrams
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-234-241
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We extend the language of influence diagrams to cope with decision scenarios where the order of decisions and observations is not determined. As the ordering of decisions is dependent on the evidence, a step-strategy of such a scenario is a sequence of dependent choices of the next action. A strategy is a step-strategy together with selection functions for decision actions. The structure of a step-strategy can be represented as a DAG with nodes labeled with action variables. We introduce the concept of GS-DAG: a DAG incorporating an optimal step-strategy for any instantiation. We give a method for constructing GS-DAGs, and we show how to use a GS-DAG for determining an optimal strategy. Finally we discuss how analysis of relevant past can be used to reduce the size of the GS-DAG.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:56:38 GMT" } ]
1,357,516,800,000
[ [ "Jensen", "Finn Verner", "" ], [ "Vomlelova", "Marta", "" ] ]
1301.0576
Mehmet Kayaalp
Mehmet Kayaalp, Gregory F. Cooper
A Bayesian Network Scoring Metric That Is Based On Globally Uniform Parameter Priors
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-251-258
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We introduce a new Bayesian network (BN) scoring metric called the Global Uniform (GU) metric. This metric is based on a particular type of default parameter prior. Such priors may be useful when a BN developer is not willing or able to specify domain-specific parameter priors. The GU parameter prior specifies that every prior joint probability distribution P consistent with a BN structure S is considered to be equally likely. Distribution P is consistent with S if P includes just the set of independence relations defined by S. We show that the GU metric addresses some undesirable behavior of the BDeu and K2 Bayesian network scoring metrics, which also use particular forms of default parameter priors. A closed form formula for computing GU for special classes of BNs is derived. Efficiently computing GU for an arbitrary BN remains an open problem.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:56:46 GMT" } ]
1,357,516,800,000
[ [ "Kayaalp", "Mehmet", "" ], [ "Cooper", "Gregory F.", "" ] ]
1301.0580
Michail Lagoudakis
Michail Lagoudakis, Ron Parr
Value Function Approximation in Zero-Sum Markov Games
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-283-292
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper investigates value function approximation in the context of zero-sum Markov games, which can be viewed as a generalization of the Markov decision process (MDP) framework to the two-agent case. We generalize error bounds from MDPs to Markov games and describe generalizations of reinforcement learning algorithms to Markov games. We present a generalization of the optimal stopping problem to a two-player simultaneous move Markov game. For this special problem, we provide stronger bounds and can guarantee convergence for LSTD and temporal difference learning with linear value function approximation. We demonstrate the viability of value function approximation for Markov games by using the Least squares policy iteration (LSPI) algorithm to learn good policies for a soccer domain and a flow control problem.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:57:02 GMT" } ]
1,357,516,800,000
[ [ "Lagoudakis", "Michail", "" ], [ "Parr", "Ron", "" ] ]
1301.0582
Uri Lerner
Uri Lerner, Brooks Moses, Maricia Scott, Sheila McIlraith, Daphne Koller
Monitoring a Complez Physical System using a Hybrid Dynamic Bayes Net
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-301-310
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The Reverse Water Gas Shift system (RWGS) is a complex physical system designed to produce oxygen from the carbon dioxide atmosphere on Mars. If sent to Mars, it would operate without human supervision, thus requiring a reliable automated system for monitoring and control. The RWGS presents many challenges typical of real-world systems, including: noisy and biased sensors, nonlinear behavior, effects that are manifested over different time granularities, and unobservability of many important quantities. In this paper we model the RWGS using a hybrid (discrete/continuous) Dynamic Bayesian Network (DBN), where the state at each time slice contains 33 discrete and 184 continuous variables. We show how the system state can be tracked using probabilistic inference over the model. We discuss how to deal with the various challenges presented by the RWGS, providing a suite of techniques that are likely to be useful in a wide range of applications. In particular, we describe a general framework for dealing with nonlinear behavior using numerical integration techniques, extending the successful Unscented Filter. We also show how to use a fixed-point computation to deal with effects that develop at different time scales, specifically rapid changes occurring during slowly changing processes. We test our model using real data collected from the RWGS, demonstrating the feasibility of hybrid DBNs for monitoring complex real-world physical systems.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:57:11 GMT" } ]
1,357,516,800,000
[ [ "Lerner", "Uri", "" ], [ "Moses", "Brooks", "" ], [ "Scott", "Maricia", "" ], [ "McIlraith", "Sheila", "" ], [ "Koller", "Daphne", "" ] ]
1301.0585
Peter McBurney
Peter McBurney, Simon Parsons
Formalizing Scenario Analysis
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-327-334
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose a formal treatment of scenarios in the context of a dialectical argumentation formalism for qualitative reasoning about uncertain propositions. Our formalism extends prior work in which arguments for and against uncertain propositions were presented and compared in interaction spaces called Agoras. We now define the notion of a scenario in this framework and use it to define a set of qualitative uncertainty labels for propositions across a collection of scenarios. This work is intended to lead to a formal theory of scenarios and scenario analysis.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:57:23 GMT" } ]
1,357,516,800,000
[ [ "McBurney", "Peter", "" ], [ "Parsons", "Simon", "" ] ]
1301.0589
Andrew Moore
Andrew Moore, Jeff Schneider
Real-valued All-Dimensions search: Low-overhead rapid searching over subsets of attributes
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-360-369
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper is about searching the combinatorial space of contingency tables during the inner loop of a nonlinear statistical optimization. Examples of this operation in various data analytic communities include searching for nonlinear combinations of attributes that contribute significantly to a regression (Statistics), searching for items to include in a decision list (machine learning) and association rule hunting (Data Mining). This paper investigates a new, efficient approach to this class of problems, called RADSEARCH (Real-valued All-Dimensions-tree Search). RADSEARCH finds the global optimum, and this gives us the opportunity to empirically evaluate the question: apart from algorithmic elegance what does this attention to optimality buy us? We compare RADSEARCH with other recent successful search algorithms such as CN2, PRIM, APriori, OPUS and DenseMiner. Finally, we introduce RADREG, a new regression algorithm for learning real-valued outputs based on RADSEARCHing for high-order interactions.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:57:39 GMT" } ]
1,357,516,800,000
[ [ "Moore", "Andrew", "" ], [ "Schneider", "Jeff", "" ] ]
1301.0590
Brenda Ng
Brenda Ng, Leonid Peshkin, Avi Pfeffer
Factored Particles for Scalable Monitoring
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-370-377
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Exact monitoring in dynamic Bayesian networks is intractable, so approximate algorithms are necessary. This paper presents a new family of approximate monitoring algorithms that combine the best qualities of the particle filtering and Boyen-Koller methods. Our algorithms maintain an approximate representation the belief state in the form of sets of factored particles, that correspond to samples of clusters of state variables. Empirical results show that our algorithms outperform both ordinary particle filtering and the Boyen-Koller algorithm on large systems.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:57:43 GMT" } ]
1,357,516,800,000
[ [ "Ng", "Brenda", "" ], [ "Peshkin", "Leonid", "" ], [ "Pfeffer", "Avi", "" ] ]
1301.0591
Uri Nodelman
Uri Nodelman, Christian R. Shelton, Daphne Koller
Continuous Time Bayesian Networks
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-378-387
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we present a language for finite state continuous time Bayesian networks (CTBNs), which describe structured stochastic processes that evolve over continuous time. The state of the system is decomposed into a set of local variables whose values change over time. The dynamics of the system are described by specifying the behavior of each local variable as a function of its parents in a directed (possibly cyclic) graph. The model specifies, at any given point in time, the distribution over two aspects: when a local variable changes its value and the next value it takes. These distributions are determined by the variable s CURRENT value AND the CURRENT VALUES OF its parents IN the graph.More formally, each variable IS modelled AS a finite state continuous time Markov process whose transition intensities are functions OF its parents.We present a probabilistic semantics FOR the language IN terms OF the generative model a CTBN defines OVER sequences OF events.We list types OF queries one might ask OF a CTBN, discuss the conceptual AND computational difficulties associated WITH exact inference, AND provide an algorithm FOR approximate inference which takes advantage OF the structure within the process.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:57:47 GMT" } ]
1,357,516,800,000
[ [ "Nodelman", "Uri", "" ], [ "Shelton", "Christian R.", "" ], [ "Koller", "Daphne", "" ] ]
1301.0592
James D. Park
James D. Park
MAP Complexity Results and Approximation Methods
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-388-396
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
MAP is the problem of finding a most probable instantiation of a set of nvariables in a Bayesian network, given some evidence. MAP appears to be a significantly harder problem than the related problems of computing the probability of evidence Pr, or MPE a special case of MAP. Because of the complexity of MAP, and the lack of viable algorithms to approximate it,MAP computations are generally avoided by practitioners. This paper investigates the complexity of MAP. We show that MAP is complete for NP. We also provide negative complexity results for elimination based algorithms. It turns out that MAP remains hard even when MPE, and Pr are easy. We show that MAP is NPcomplete when the networks are restricted to polytrees, and even then can not be effectively approximated. Because there is no approximation algorithm with guaranteed results, we investigate best effort approximations. We introduce a generic MAP approximation framework. As one instantiation of it, we implement local search coupled with belief propagation BP to approximate MAP. We show how to extract approximate evidence retraction information from belief propagation which allows us to perform efficient local search. This allows MAP approximation even on networks that are too complex to even exactly solve the easier problems of computing Pr or MPE. Experimental results indicate that using BP and local search provides accurate MAP estimates in many cases.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:57:50 GMT" } ]
1,357,516,800,000
[ [ "Park", "James D.", "" ] ]
1301.0596
Silja Renooij
Silja Renooij, Linda C. van der Gaag
From Qualitative to Quantitative Probabilistic Networks
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-422-429
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Quantification is well known to be a major obstacle in the construction of a probabilistic network, especially when relying on human experts for this purpose. The construction of a qualitative probabilistic network has been proposed as an initial step in a network s quantification, since the qualitative network can be used TO gain preliminary insight IN the projected networks reasoning behaviour. We extend on this idea and present a new type of network in which both signs and numbers are specified; we further present an associated algorithm for probabilistic inference. Building upon these semi-qualitative networks, a probabilistic network can be quantified and studied in a stepwise manner. As a result, modelling inadequacies can be detected and amended at an early stage in the quantification process.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:58:05 GMT" } ]
1,357,516,800,000
[ [ "Renooij", "Silja", "" ], [ "van der Gaag", "Linda C.", "" ] ]
1301.0597
Jose Carlos Ferreira da Rocha
Jose Carlos Ferreira da Rocha, Fabio Gagliardi Cozman
Inference with Seperately Specified Sets of Probabilities in Credal Networks
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-430-437
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present new algorithms for inference in credal networks --- directed acyclic graphs associated with sets of probabilities. Credal networks are here interpreted as encoding strong independence relations among variables. We first present a theory of credal networks based on separately specified sets of probabilities. We also show that inference with polytrees is NP-hard in this setting. We then introduce new techniques that reduce the computational effort demanded by inference, particularly in polytrees, by exploring separability of credal sets.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:58:09 GMT" } ]
1,357,516,800,000
[ [ "da Rocha", "Jose Carlos Ferreira", "" ], [ "Cozman", "Fabio Gagliardi", "" ] ]
1301.0603
Masami Takikawa
Masami Takikawa, Bruce D'Ambrosio, Ed Wright
Real-Time Inference with Large-Scale Temporal Bayes Nets
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-477-484
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
An increasing number of applications require real-time reasoning under uncertainty with streaming input. The temporal (dynamic) Bayes net formalism provides a powerful representational framework for such applications. However, existing exact inference algorithms for dynamic Bayes nets do not scale to the size of models required for real world applications which often contain hundreds or even thousands of variables for each time slice. In addition, existing algorithms were not developed with real-time processing in mind. We have developed a new computational approach to support real-time exact inference in large temporal Bayes nets. Our approach tackles scalability by recognizing that the complexity of the inference depends on the number of interface nodes between time slices and by exploiting the distinction between static and dynamic nodes in order to reduce the number of interface nodes and to factorize their joint probability distribution. We approach the real-time issue by organizing temporal Bayes nets into static representations, and then using the symbolic probabilistic inference algorithm to derive analytic expressions for the static representations. The parts of these expressions that do not change at each time step are pre-computed. The remaining parts are compiled into efficient procedural code so that the memory and CPU resources required by the inference are small and fixed.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:58:34 GMT" } ]
1,357,516,800,000
[ [ "Takikawa", "Masami", "" ], [ "D'Ambrosio", "Bruce", "" ], [ "Wright", "Ed", "" ] ]
1301.0605
Sekhar Tatikonda
Sekhar Tatikonda, Michael I. Jordan
Loopy Belief Propogation and Gibbs Measures
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-493-500
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We address the question of convergence in the loopy belief propagation (LBP) algorithm. Specifically, we relate convergence of LBP to the existence of a weak limit for a sequence of Gibbs measures defined on the LBP s associated computation tree.Using tools FROM the theory OF Gibbs measures we develop easily testable sufficient conditions FOR convergence.The failure OF convergence OF LBP implies the existence OF multiple phases FOR the associated Gibbs specification.These results give new insight INTO the mechanics OF the algorithm.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:58:42 GMT" } ]
1,357,516,800,000
[ [ "Tatikonda", "Sekhar", "" ], [ "Jordan", "Michael I.", "" ] ]
1301.0606
Sylvie Thiebaux
Sylvie Thiebaux, Froduald Kabanza, John Slanley
Anytime State-Based Solution Methods for Decision Processes with non-Markovian Rewards
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-501-510
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A popular approach to solving a decision process with non-Markovian rewards (NMRDP) is to exploit a compact representation of the reward function to automatically translate the NMRDP into an equivalent Markov decision process (MDP) amenable to our favorite MDP solution method. The contribution of this paper is a representation of non-Markovian reward functions and a translation into MDP aimed at making the best possible use of state-based anytime algorithms as the solution method. By explicitly constructing and exploring only parts of the state space, these algorithms are able to trade computation time for policy quality, and have proven quite effective in dealing with large MDPs. Our representation extends future linear temporal logic (FLTL) to express rewards. Our translation has the effect of embedding model-checking in the solution method. It results in an MDP of the minimal size achievable without stepping outside the anytime framework, and consequently in better policies by the deadline.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:58:46 GMT" } ]
1,357,516,800,000
[ [ "Thiebaux", "Sylvie", "" ], [ "Kabanza", "Froduald", "" ], [ "Slanley", "John", "" ] ]
1301.0608
Jin Tian
Jin Tian, Judea Pearl
On the Testable Implications of Causal Models with Hidden Variables
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-519-527
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The validity OF a causal model can be tested ONLY IF the model imposes constraints ON the probability distribution that governs the generated data. IN the presence OF unmeasured variables, causal models may impose two types OF constraints : conditional independencies, AS READ through the d - separation criterion, AND functional constraints, FOR which no general criterion IS available.This paper offers a systematic way OF identifying functional constraints AND, thus, facilitates the task OF testing causal models AS well AS inferring such models FROM data.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:58:54 GMT" } ]
1,357,516,800,000
[ [ "Tian", "Jin", "" ], [ "Pearl", "Judea", "" ] ]
1301.0609
Jirka Vomlel
Jirka Vomlel
Exploiting Functional Dependence in Bayesian Network Inference
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-528-535
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose an efficient method for Bayesian network inference in models with functional dependence. We generalize the multiplicative factorization method originally designed by Takikawa and D Ambrosio(1999) FOR models WITH independence OF causal influence.Using a hidden variable, we transform a probability potential INTO a product OF two - dimensional potentials.The multiplicative factorization yields more efficient inference. FOR example, IN junction tree propagation it helps TO avoid large cliques. IN ORDER TO keep potentials small, the number OF states OF the hidden variable should be minimized.We transform this problem INTO a combinatorial problem OF minimal base IN a particular space.We present an example OF a computerized adaptive test, IN which the factorization method IS significantly more efficient than previous inference methods.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:58:58 GMT" } ]
1,357,516,800,000
[ [ "Vomlel", "Jirka", "" ] ]
1301.0611
Peter P. Wakker
Peter P. Wakker
Decision Principles to justify Carnap's Updating Method and to Suggest Corrections of Probability Judgments (Invited Talks)
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-544-551
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper uses decision-theoretic principles to obtain new insights into the assessment and updating of probabilities. First, a new foundation of Bayesianism is given. It does not require infinite atomless uncertainties as did Savage s classical result, AND can therefore be applied TO ANY finite Bayesian network.It neither requires linear utility AS did de Finetti s classical result, AND r ntherefore allows FOR the empirically AND normatively desirable risk r naversion.Finally, BY identifying AND fixing utility IN an elementary r nmanner, our result can readily be applied TO identify methods OF r nprobability updating.Thus, a decision - theoretic foundation IS given r nto the computationally efficient method OF inductive reasoning r ndeveloped BY Rudolf Carnap.Finally, recent empirical findings ON r nprobability assessments are discussed.It leads TO suggestions FOR r ncorrecting biases IN probability assessments, AND FOR an alternative r nto the Dempster - Shafer belief functions that avoids the reduction TO r ndegeneracy after multiple updatings.r n
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:59:06 GMT" } ]
1,357,516,800,000
[ [ "Wakker", "Peter P.", "" ] ]
1301.0614
Sung Wook Yoon
Sung Wook Yoon, Alan Fern, Robert Givan
Inductive Policy Selection for First-Order MDPs
Appears in Proceedings of the Eighteenth Conference on Uncertainty in Artificial Intelligence (UAI2002)
null
null
UAI-P-2002-PG-568-576
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We select policies for large Markov Decision Processes (MDPs) with compact first-order representations. We find policies that generalize well as the number of objects in the domain grows, potentially without bound. Existing dynamic-programming approaches based on flat, propositional, or first-order representations either are impractical here or do not naturally scale as the number of objects grows without bound. We implement and evaluate an alternative approach that induces first-order policies using training data constructed by solving small problem instances using PGraphplan (Blum & Langford, 1999). Our policies are represented as ensembles of decision lists, using a taxonomic concept language. This approach extends the work of Martin and Geffner (2000) to stochastic domains, ensemble learning, and a wider variety of problems. Empirically, we find "good" policies for several stochastic first-order MDPs that are beyond the scope of previous approaches. We also discuss the application of this work to the relational reinforcement-learning problem.
[ { "version": "v1", "created": "Wed, 12 Dec 2012 15:59:19 GMT" } ]
1,357,516,800,000
[ [ "Yoon", "Sung Wook", "" ], [ "Fern", "Alan", "" ], [ "Givan", "Robert", "" ] ]
1301.1385
Michael Fink
Mario Alviano and Wolfgang Faber
Translating NP-SPEC into ASP
Proceedings of Answer Set Programming and Other Computing Paradigms (ASPOCP 2012), 5th International Workshop, September 4, 2012, Budapest, Hungary
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
NP-SPEC is a language for specifying problems in NP in a declarative way. Despite the fact that the semantics of the language was given by referring to Datalog with circumscription, which is very close to ASP, so far the only existing implementations are by means of ECLiPSe Prolog and via Boolean satisfiability solvers. In this paper, we present translations from NP-SPEC into various forms of ASP and analyze them. We also argue that it might be useful to incorporate certain language constructs of NP-SPEC into mainstream ASP.
[ { "version": "v1", "created": "Tue, 8 Jan 2013 02:28:49 GMT" } ]
1,357,689,600,000
[ [ "Alviano", "Mario", "" ], [ "Faber", "Wolfgang", "" ] ]
1301.1387
Michael Fink
Marcello Balduccini and Michael Gelfond
Language ASP{f} with Arithmetic Expressions and Consistency-Restoring Rules
Proceedings of Answer Set Programming and Other Computing Paradigms (ASPOCP 2012), 5th International Workshop, September 4, 2012, Budapest, Hungary
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we continue the work on our extension of Answer Set Programming by non-Herbrand functions and add to the language support for arithmetic expressions and various inequality relations over non-Herbrand functions, as well as consistency-restoring rules from CR-Prolog. We demonstrate the use of this latest version of the language in the representation of important kinds of knowledge.
[ { "version": "v1", "created": "Tue, 8 Jan 2013 02:29:05 GMT" } ]
1,357,689,600,000
[ [ "Balduccini", "Marcello", "" ], [ "Gelfond", "Michael", "" ] ]
1301.1388
Michael Fink
G\"unther Charwat, Johannes Peter Wallner, and Stefan Woltran
Utilizing ASP for Generating and Visualizing Argumentation Frameworks
Proceedings of Answer Set Programming and Other Computing Paradigms (ASPOCP 2012), 5th International Workshop, September 4, 2012, Budapest, Hungary
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Within the area of computational models of argumentation, the instantiation-based approach is gaining more and more attention, not at least because meaningful input for Dung's abstract frameworks is provided in that way. In a nutshell, the aim of instantiation-based argumentation is to form, from a given knowledge base, a set of arguments and to identify the conflicts between them. The resulting network is then evaluated by means of extension-based semantics on an abstract level, i.e. on the resulting graph. While several systems are nowadays available for the latter step, the automation of the instantiation process itself has received less attention. In this work, we provide a novel approach to construct and visualize an argumentation framework from a given knowledge base. The system we propose relies on Answer-Set Programming and follows a two-step approach. A first program yields the logic-based arguments as its answer-sets; a second program is then used to specify the relations between arguments based on the answer-sets of the first program. As it turns out, this approach not only allows for a flexible and extensible tool for instantiation-based argumentation, but also provides a new method for answer-set visualization in general.
[ { "version": "v1", "created": "Tue, 8 Jan 2013 02:29:11 GMT" } ]
1,357,689,600,000
[ [ "Charwat", "Günther", "" ], [ "Wallner", "Johannes Peter", "" ], [ "Woltran", "Stefan", "" ] ]
1301.1389
Michael Fink
Sandeep Chintabathina
Planning and Scheduling in Hybrid Domains Using Answer Set Programming
Proceedings of Answer Set Programming and Other Computing Paradigms (ASPOCP 2012), 5th International Workshop, September 4, 2012, Budapest, Hungary
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we present an Action Language-Answer Set Programming based approach to solving planning and scheduling problems in hybrid domains - domains that exhibit both discrete and continuous behavior. We use action language H to represent the domain and then translate the resulting theory into an A-Prolog program. In this way, we reduce the problem of finding solutions to planning and scheduling problems to computing answer sets of A-Prolog programs. We cite a planning and scheduling example from the literature and show how to model it in H. We show how to translate the resulting H theory into an equivalent A-Prolog program. We compute the answer sets of the resulting program using a hybrid solver called EZCSP which loosely integrates a constraint solver with an answer set solver. The solver allows us reason about constraints over reals and compute solutions to complex planning and scheduling problems. Results have shown that our approach can be applied to any planning and scheduling problem in hybrid domains.
[ { "version": "v1", "created": "Tue, 8 Jan 2013 02:29:17 GMT" } ]
1,357,689,600,000
[ [ "Chintabathina", "Sandeep", "" ] ]
1301.1392
Michael Fink
Martin Gebser, Torsten Grote, Roland Kaminski, Philipp Obermeier, Orkunt Sabuncu, and Torsten Schaub
Answer Set Programming for Stream Reasoning
Proceedings of Answer Set Programming and Other Computing Paradigms (ASPOCP 2012), 5th International Workshop, September 4, 2012, Budapest, Hungary
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The advance of Internet and Sensor technology has brought about new challenges evoked by the emergence of continuous data streams. Beyond rapid data processing, application areas like ambient assisted living, robotics, or dynamic scheduling involve complex reasoning tasks. We address such scenarios and elaborate upon approaches to knowledge-intense stream reasoning, based on Answer Set Programming (ASP). While traditional ASP methods are devised for singular problem solving, we develop new techniques to formulate and process problems dealing with emerging as well as expiring data in a seamless way.
[ { "version": "v1", "created": "Tue, 8 Jan 2013 02:29:44 GMT" } ]
1,357,689,600,000
[ [ "Gebser", "Martin", "" ], [ "Grote", "Torsten", "" ], [ "Kaminski", "Roland", "" ], [ "Obermeier", "Philipp", "" ], [ "Sabuncu", "Orkunt", "" ], [ "Schaub", "Torsten", "" ] ]
1301.2005
Xiaowang Zhang
Xiaowang Zhang and Kewen Wang and Zhe Wang and Yue Ma and Guilin Qi
A Distance-based Paraconsistent Semantics for DL-Lite
17 pages
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
DL-Lite is an important family of description logics. Recently, there is an increasing interest in handling inconsistency in DL-Lite as the constraint imposed by a TBox can be easily violated by assertions in ABox in DL-Lite. In this paper, we present a distance-based paraconsistent semantics based on the notion of feature in DL-Lite, which provides a novel way to rationally draw meaningful conclusions even from an inconsistent knowledge base. Finally, we investigate several important logical properties of this entailment relation based on the new semantics and show its promising advantages in non-monotonic reasoning for DL-Lite.
[ { "version": "v1", "created": "Wed, 9 Jan 2013 23:02:34 GMT" }, { "version": "v2", "created": "Wed, 23 Jan 2013 14:57:25 GMT" }, { "version": "v3", "created": "Wed, 3 Jun 2015 07:03:58 GMT" } ]
1,433,376,000,000
[ [ "Zhang", "Xiaowang", "" ], [ "Wang", "Kewen", "" ], [ "Wang", "Zhe", "" ], [ "Ma", "Yue", "" ], [ "Qi", "Guilin", "" ] ]
1301.2137
Xiaowang Zhang
Dai Xu and Xiaowang Zhang and Zuoquan Lin
A Forgetting-based Approach to Merging Knowledge Bases
5 pages
2010 International Conference on Progress in Informatics and Computing, IEEE Computer Society, vol 1, pp. 321-325
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper presents a novel approach based on variable forgetting, which is a useful tool in resolving contradictory by filtering some given variables, to merging multiple knowledge bases. This paper first builds a relationship between belief merging and variable forgetting by using dilation. Variable forgetting is applied to capture belief merging operation. Finally, some new merging operators are developed by modifying candidate variables to amend the shortage of traditional merging operators. Different from model selection of traditional merging operators, as an alternative approach, variable selection in those new operators could provide intuitive information about an atom variable among whole knowledge bases.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 14:41:52 GMT" } ]
1,357,862,400,000
[ [ "Xu", "Dai", "" ], [ "Zhang", "Xiaowang", "" ], [ "Lin", "Zuoquan", "" ] ]
1301.2146
Xiaowang Zhang
Xiaowang Zhang and Guohui Xiao and Zuoquan Lin
A Paraconsistent Tableau Algorithm Based on Sign Transformation in Semantic Web
11 pages, in Chinese; the 4th Chinese Semantic Web Symposium (CSWS 2010), Beijing, China
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In an open, constantly changing and collaborative environment like the forthcoming Semantic Web, it is reasonable to expect that knowledge sources will contain noise and inaccuracies. It is well known, as the logical foundation of the Semantic Web, description logic is lack of the ability of tolerating inconsistent or incomplete data. Recently, the ability of paraconsistent approaches in Semantic Web is weaker in this paper, we present a tableau algorithm based on sign transformation in Semantic Web which holds the stronger ability of reasoning. We prove that the tableau algorithm is decidable which hold the same function of classical tableau algorithm for consistent knowledge bases.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 15:07:22 GMT" } ]
1,357,862,400,000
[ [ "Zhang", "Xiaowang", "" ], [ "Xiao", "Guohui", "" ], [ "Lin", "Zuoquan", "" ] ]
1301.2215
Michael Fink
Michael Fink and Yuliya Lierler
Proceedings of Answer Set Programming and Other Computing Paradigms (ASPOCP 2012), 5th International Workshop, September 4, 2012, Budapest, Hungary
null
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This volume contains the papers presented at the fifth workshop on Answer Set Programming and Other Computing Paradigms (ASPOCP 2012) held on September 4th, 2012 in Budapest, co-located with the 28th International Conference on Logic Programming (ICLP 2012). It thus continues a series of previous events co-located with ICLP, aiming at facilitating the discussion about crossing the boundaries of current ASP techniques in theory, solving, and applications, in combination with or inspired by other computing paradigms.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 18:52:32 GMT" } ]
1,357,862,400,000
[ [ "Fink", "Michael", "" ], [ "Lierler", "Yuliya", "" ] ]
1301.2254
Nicos Angelopoulos
Nicos Angelopoulos, James Cussens
Markov Chain Monte Carlo using Tree-Based Priors on Model Structure
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-16-23
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present a general framework for defining priors on model structure and sampling from the posterior using the Metropolis-Hastings algorithm. The key idea is that structure priors are defined via a probability tree and that the proposal mechanism for the Metropolis-Hastings algorithm operates by traversing this tree, thereby defining a cheaply computable acceptance probability. We have applied this approach to Bayesian net structure learning using a number of priors and tree traversal strategies. Our results show that these must be chosen appropriately for this approach to be successful.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:22:27 GMT" } ]
1,358,121,600,000
[ [ "Angelopoulos", "Nicos", "" ], [ "Cussens", "James", "" ] ]
1301.2255
Salem Benferhat
Salem Benferhat, Didier Dubois, Souhila Kaci, Henri Prade
Graphical readings of possibilistic logic bases
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-24-31
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Possibility theory offers either a qualitive, or a numerical framework for representing uncertainty, in terms of dual measures of possibility and necessity. This leads to the existence of two kinds of possibilistic causal graphs where the conditioning is either based on the minimum, or the product operator. Benferhat et al. (1999) have investigated the connections between min-based graphs and possibilistic logic bases (made of classical formulas weighted in terms of certainty). This paper deals with a more difficult issue : the product-based graphical representations of possibilistic bases, which provides an easy structural reading of possibilistic bases. Moreover, this paper also provides another reading of possibilistic bases in terms of comparative preferences of the form "in the context p, q is preferred to not q". This enables us to explicit preferences underlying a set of goals with different levels of priority.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:22:32 GMT" } ]
1,358,121,600,000
[ [ "Benferhat", "Salem", "" ], [ "Dubois", "Didier", "" ], [ "Kaci", "Souhila", "" ], [ "Prade", "Henri", "" ] ]
1301.2257
Blai Bonet
Blai Bonet
A Calculus for Causal Relevance
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-40-47
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper presents a sound and completecalculus for causal relevance, based onPearl's functional models semantics.The calculus consists of axioms and rulesof inference for reasoning about causalrelevance relationships.We extend the set of known axioms for causalrelevance with three new axioms, andintroduce two new rules of inference forreasoning about specific subclasses ofmodels.These subclasses give a more refinedcharacterization of causal models than the one given in Halpern's axiomatizationof counterfactual reasoning.Finally, we show how the calculus for causalrelevance can be used in the task ofidentifying causal structure from non-observational data.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:22:40 GMT" } ]
1,358,121,600,000
[ [ "Bonet", "Blai", "" ] ]
1301.2259
Craig Boutilier
Craig Boutilier, Fahiem Bacchus, Ronen I. Brafman
UCP-Networks: A Directed Graphical Representation of Conditional Utilities
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-56-64
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose a new directed graphical representation of utility functions, called UCP-networks, that combines aspects of two existing graphical models: generalized additive models and CP-networks. The network decomposes a utility function into a number of additive factors, with the directionality of the arcs reflecting conditional dependence of preference statements - in the underlying (qualitative) preference ordering - under a {em ceteris paribus} (all else being equal) interpretation. This representation is arguably natural in many settings. Furthermore, the strong CP-semantics ensures that computation of optimization and dominance queries is very efficient. We also demonstrate the value of this representation in decision making. Finally, we describe an interactive elicitation procedure that takes advantage of the linear nature of the constraints on "`tradeoff weights" imposed by a UCP-network. This procedure allows the network to be refined until the regret of the decision with minimax regret (with respect to the incompletely specified utility function) falls below a specified threshold (e.g., the cost of further questioning.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:22:49 GMT" } ]
1,358,121,600,000
[ [ "Boutilier", "Craig", "" ], [ "Bacchus", "Fahiem", "" ], [ "Brafman", "Ronen I.", "" ] ]
1301.2260
Jian Cheng
Jian Cheng, Marek J. Druzdzel
Confidence Inference in Bayesian Networks
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-75-82
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present two sampling algorithms for probabilistic confidence inference in Bayesian networks. These two algorithms (we call them AIS-BN-mu and AIS-BN-sigma algorithms) guarantee that estimates of posterior probabilities are with a given probability within a desired precision bound. Our algorithms are based on recent advances in sampling algorithms for (1) estimating the mean of bounded random variables and (2) adaptive importance sampling in Bayesian networks. In addition to a simple stopping rule for sampling that they provide, the AIS-BN-mu and AIS-BN-sigma algorithms are capable of guiding the learning process in the AIS-BN algorithm. An empirical evaluation of the proposed algorithms shows excellent performance, even for very unlikely evidence.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:22:53 GMT" } ]
1,358,121,600,000
[ [ "Cheng", "Jian", "" ], [ "Druzdzel", "Marek J.", "" ] ]
1301.2263
David Danks
David Danks, Clark Glymour
Linearity Properties of Bayes Nets with Binary Variables
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-98-104
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
It is "well known" that in linear models: (1) testable constraints on the marginal distribution of observed variables distinguish certain cases in which an unobserved cause jointly influences several observed variables; (2) the technique of "instrumental variables" sometimes permits an estimation of the influence of one variable on another even when the association between the variables may be confounded by unobserved common causes; (3) the association (or conditional probability distribution of one variable given another) of two variables connected by a path or trek can be computed directly from the parameter values associated with each edge in the path or trek; (4) the association of two variables produced by multiple treks can be computed from the parameters associated with each trek; and (5) the independence of two variables conditional on a third implies the corresponding independence of the sums of the variables over all units conditional on the sums over all units of each of the original conditioning variables.These properties are exploited in search procedures. It is also known that properties (2)-(5) do not hold for all Bayes nets with binary variables. We show that (1) holds for all Bayes nets with binary variables and (5) holds for all singly trek-connected Bayes nets of that kind. We further show that all five properties hold for Bayes nets with any DAG and binary variables parameterized with noisy-or and noisy-and gates.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:23:05 GMT" } ]
1,358,121,600,000
[ [ "Danks", "David", "" ], [ "Glymour", "Clark", "" ] ]
1301.2265
Rina Dechter
Rina Dechter, David Ephraim Larkin
Hybrid Processing of Beliefs and Constraints
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-112-119
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper explores algorithms for processing probabilistic and deterministic information when the former is represented as a belief network and the latter as a set of boolean clauses. The motivating tasks are 1. evaluating beliefs networks having a large number of deterministic relationships and2. evaluating probabilities of complex boolean querie over a belief network. We propose a parameterized family of variable elimination algorithms that exploit both types of information, and that allows varying levels of constraint propagation inferences. The complexity of the scheme is controlled by the induced-width of the graph {em augmented} by the dependencies introduced by the boolean constraints. Preliminary empirical evaluation demonstrate the effect of constraint propagation on probabilistic computation.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:23:13 GMT" } ]
1,358,121,600,000
[ [ "Dechter", "Rina", "" ], [ "Larkin", "David Ephraim", "" ] ]
1301.2271
Phan H. Giang
Phan H. Giang, Prakash P. Shenoy
A Comparison of Axiomatic Approaches to Qualitative Decision Making Using Possibility Theory
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-162-170
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we analyze two recent axiomatic approaches proposed by Dubois et al and by Giang and Shenoy to qualitative decision making where uncertainty is described by possibility theory. Both axiomtizations are inspired by von Neumann and Morgenstern's system of axioms for the case of probability theory. We show that our approach naturally unifies two axiomatic systems that correspond respectively to pessimistic and optimistic decision criteria proposed by Dubois et al. The simplifying unification is achieved by (i) replacing axioms that are supposed to reflect two informational attitudes (uncertainty aversion and uncertainty attraction) by an axiom that imposes order on set of standard lotteries and (ii) using a binary utility scale in which each utility level is represented by a pair of numbers.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:23:40 GMT" } ]
1,358,121,600,000
[ [ "Giang", "Phan H.", "" ], [ "Shenoy", "Prakash P.", "" ] ]
1301.2272
Steven B. Gillispie
Steven B. Gillispie, Michael D. Perlman
Enumerating Markov Equivalence Classes of Acyclic Digraph Models
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-171-177
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Graphical Markov models determined by acyclic digraphs (ADGs), also called directed acyclic graphs (DAGs), are widely studied in statistics, computer science (as Bayesian networks), operations research (as influence diagrams), and many related fields. Because different ADGs may determine the same Markov equivalence class, it long has been of interest to determine the efficiency gained in model specification and search by working directly with Markov equivalence classes of ADGs rather than with ADGs themselves. A computer program was written to enumerate the equivalence classes of ADG models as specified by Pearl & Verma's equivalence criterion. The program counted equivalence classes for models up to and including 10 vertices. The ratio of number of classes to ADGs appears to approach an asymptote of about 0.267. Classes were analyzed according to number of edges and class size. By edges, the distribution of number of classes approaches a Gaussian shape. By class size, classes of size 1 are most common, with the proportions for larger sizes initially decreasing but then following a more irregular pattern. The maximum number of classes generated by any undirected graph was found to increase approximately factorially. The program also includes a new variation of orderly algorithm for generating undirected graphs.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:23:44 GMT" } ]
1,358,121,600,000
[ [ "Gillispie", "Steven B.", "" ], [ "Perlman", "Michael D.", "" ] ]
1301.2274
Vu A. Ha
Vu A. Ha, Peter Haddawy, John Miyamoto
Similarity Measures on Preference Structures, Part II: Utility Functions
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-186-193
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In previous work cite{Ha98:Towards} we presented a case-based approach to eliciting and reasoning with preferences. A key issue in this approach is the definition of similarity between user preferences. We introduced the probabilistic distance as a measure of similarity on user preferences, and provided an algorithm to compute the distance between two partially specified {em value} functions. This is for the case of decision making under {em certainty}. In this paper we address the more challenging issue of computing the probabilistic distance in the case of decision making under{em uncertainty}. We provide an algorithm to compute the probabilistic distance between two partially specified {em utility} functions. We demonstrate the use of this algorithm with a medical data set of partially specified patient preferences,where none of the other existing distancemeasures appear definable. Using this data set, we also demonstrate that the case-based approach to preference elicitation isapplicable in domains with uncertainty. Finally, we provide a comprehensive analytical comparison of the probabilistic distance with some existing distance measures on preferences.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:23:53 GMT" } ]
1,358,121,600,000
[ [ "Ha", "Vu A.", "" ], [ "Haddawy", "Peter", "" ], [ "Miyamoto", "John", "" ] ]
1301.2275
Joseph Y. Halpern
Joseph Y. Halpern, Judea Pearl
Causes and Explanations: A Structural-Model Approach --- Part 1: Causes
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001), later extended version is arXiv:cs/0011012
null
null
UAI-P-2001-PG-194-202
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose a new definition of actual causes, using structural equations to model counterfactuals.We show that the definitions yield a plausible and elegant account ofcausation that handles well examples which have caused problems forother definitions and resolves major difficulties in the traditionalaccount. In a companion paper, we show how the definition of causality can beused to give an elegant definition of (causal) explanation.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:23:57 GMT" } ]
1,358,121,600,000
[ [ "Halpern", "Joseph Y.", "" ], [ "Pearl", "Judea", "" ] ]
1301.2279
Eric J. Horvitz
Eric J. Horvitz, Yongshao Ruan, Carla P. Gomes, Henry Kautz, Bart Selman, David Maxwell Chickering
A Bayesian Approach to Tackling Hard Computational Problems
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-235-244
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We are developing a general framework for using learned Bayesian models for decision-theoretic control of search and reasoningalgorithms. We illustrate the approach on the specific task of controlling both general and domain-specific solvers on a hard class of structured constraint satisfaction problems. A successful strategyfor reducing the high (and even infinite) variance in running time typically exhibited by backtracking search algorithms is to cut off and restart the search if a solution is not found within a certainamount of time. Previous work on restart strategies have employed fixed cut off values. We show how to create a dynamic cut off strategy by learning a Bayesian model that predicts the ultimate length of a trial based on observing the early behavior of the search algorithm. Furthermore, we describe the general conditions under which a dynamic restart strategy can outperform the theoretically optimal fixed strategy.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:24:15 GMT" } ]
1,358,121,600,000
[ [ "Horvitz", "Eric J.", "" ], [ "Ruan", "Yongshao", "" ], [ "Gomes", "Carla P.", "" ], [ "Kautz", "Henry", "" ], [ "Selman", "Bart", "" ], [ "Chickering", "David Maxwell", "" ] ]
1301.2282
Tomas Kocka
Tomas Kocka, Remco R. Bouckaert, Milan Studeny
On characterizing Inclusion of Bayesian Networks
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-261-268
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Every directed acyclic graph (DAG) over a finite non-empty set of variables (= nodes) N induces an independence model over N, which is a list of conditional independence statements over N.The inclusion problem is how to characterize (in graphical terms) whether all independence statements in the model induced by a DAG K are in the model induced by a second DAG L. Meek (1997) conjectured that this inclusion holds iff there exists a sequence of DAGs from L to K such that only certain 'legal' arrow reversal and 'legal' arrow adding operations are performed to get the next DAG in the sequence.In this paper we give several characterizations of inclusion of DAG models and verify Meek's conjecture in the case that the DAGs K and L differ in at most one adjacency. As a warming up a rigorous proof of well-known graphical characterizations of equivalence of DAGs, which is a highly related problem, is given.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:24:28 GMT" } ]
1,358,121,600,000
[ [ "Kocka", "Tomas", "" ], [ "Bouckaert", "Remco R.", "" ], [ "Studeny", "Milan", "" ] ]
1301.2285
Jerome Lang
Jerome Lang, Philippe Muller
Plausible reasoning from spatial observations
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-285-292
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This article deals with plausible reasoning from incomplete knowledge about large-scale spatial properties. The availableinformation, consisting of a set of pointwise observations,is extrapolated to neighbour points. We make use of belief functions to represent the influence of the knowledge at a given point to another point; the quantitative strength of this influence decreases when the distance between both points increases. These influences arethen aggregated using a variant of Dempster's rule of combination which takes into account the relative dependence between observations.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:24:41 GMT" } ]
1,358,121,600,000
[ [ "Lang", "Jerome", "" ], [ "Muller", "Philippe", "" ] ]
1301.2287
Kathryn Blackmond Laskey
Kathryn Blackmond Laskey, Suzanne M. Mahoney, Ed Wright
Hypothesis Management in Situation-Specific Network Construction
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-301-309
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper considers the problem of knowledge-based model construction in the presence of uncertainty about the association of domain entities to random variables. Multi-entity Bayesian networks (MEBNs) are defined as a representation for knowledge in domains characterized by uncertainty in the number of relevant entities, their interrelationships, and their association with observables. An MEBN implicitly specifies a probability distribution in terms of a hierarchically structured collection of Bayesian network fragments that together encode a joint probability distribution over arbitrarily many interrelated hypotheses. Although a finite query-complete model can always be constructed, association uncertainty typically makes exact model construction and evaluation intractable. The objective of hypothesis management is to balance tractability against accuracy. We describe an application to the problem of using intelligence reports to infer the organization and activities of groups of military vehicles. Our approach is compared to related work in the tracking and fusion literature.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:24:50 GMT" } ]
1,358,121,600,000
[ [ "Laskey", "Kathryn Blackmond", "" ], [ "Mahoney", "Suzanne M.", "" ], [ "Wright", "Ed", "" ] ]
1301.2288
Uri Lerner
Uri Lerner, Ron Parr
Inference in Hybrid Networks: Theoretical Limits and Practical Algorithms
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-310-318
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
An important subclass of hybrid Bayesian networks are those that represent Conditional Linear Gaussian (CLG) distributions --- a distribution with a multivariate Gaussian component for each instantiation of the discrete variables. In this paper we explore the problem of inference in CLGs. We show that inference in CLGs can be significantly harder than inference in Bayes Nets. In particular, we prove that even if the CLG is restricted to an extremely simple structure of a polytree in which every continuous node has at most one discrete ancestor, the inference task is NP-hard.To deal with the often prohibitive computational cost of the exact inference algorithm for CLGs, we explore several approximate inference algorithms. These algorithms try to find a small subset of Gaussians which are a good approximation to the full mixture distribution. We consider two Monte Carlo approaches and a novel approach that enumerates mixture components in order of prior probability. We compare these methods on a variety of problems and show that our novel algorithm is very promising for large, hybrid diagnosis problems.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:24:54 GMT" } ]
1,358,121,600,000
[ [ "Lerner", "Uri", "" ], [ "Parr", "Ron", "" ] ]
1301.2289
Uri Lerner
Uri Lerner, Eran Segal, Daphne Koller
Exact Inference in Networks with Discrete Children of Continuous Parents
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-319-328
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Many real life domains contain a mixture of discrete and continuous variables and can be modeled as hybrid Bayesian Networks. Animportant subclass of hybrid BNs are conditional linear Gaussian (CLG) networks, where the conditional distribution of the continuous variables given an assignment to the discrete variables is a multivariate Gaussian. Lauritzen's extension to the clique tree algorithm can be used for exact inference in CLG networks. However, many domains also include discrete variables that depend on continuous ones, and CLG networks do not allow such dependencies to berepresented. No exact inference algorithm has been proposed for these enhanced CLG networks. In this paper, we generalize Lauritzen's algorithm, providing the first "exact" inference algorithm for augmented CLG networks - networks where continuous nodes are conditional linear Gaussians but that also allow discrete children ofcontinuous parents. Our algorithm is exact in the sense that it computes the exact distributions over the discrete nodes, and the exact first and second moments of the continuous ones, up to the accuracy obtained by numerical integration used within thealgorithm. When the discrete children are modeled with softmax CPDs (as is the case in many real world domains) the approximation of the continuous distributions using the first two moments is particularly accurate. Our algorithm is simple to implement and often comparable in its complexity to Lauritzen's algorithm. We show empirically that it achieves substantially higher accuracy than previous approximate algorithms.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:24:58 GMT" } ]
1,358,121,600,000
[ [ "Lerner", "Uri", "" ], [ "Segal", "Eran", "" ], [ "Koller", "Daphne", "" ] ]
1301.2290
Thomas Lukasiewicz
Thomas Lukasiewicz
Probabilistic Logic Programming under Inheritance with Overriding
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-329-336
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present probabilistic logic programming under inheritance with overriding. This approach is based on new notions of entailment for reasoning with conditional constraints, which are obtained from the classical notion of logical entailment by adding the principle of inheritance with overriding. This is done by using recent approaches to probabilistic default reasoning with conditional constraints. We analyze the semantic properties of the new entailment relations. We also present algorithms for probabilistic logic programming under inheritance with overriding, and program transformations for an increased efficiency.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:25:03 GMT" } ]
1,358,121,600,000
[ [ "Lukasiewicz", "Thomas", "" ] ]
1301.2291
Anders L. Madsen
Anders L. Madsen, Dennis Nilsson
Solving Influence Diagrams using HUGIN, Shafer-Shenoy and Lazy Propagation
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-337-345
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we compare three different architectures for the evaluation of influence diagrams: HUGIN, Shafer-Shenoy, and Lazy Evaluation architecture. The computational complexity of the architectures are compared on the LImited Memory Influence Diagram (LIMID): a diagram where only the requiste information for the computation of the optimal policies are depicted. Because the requsite information is explicitly represented in the LIMID the evaluation can take advantage of it, and significant savings in computational can be obtained. In this paper we show how the obtained savings is considerably increased when the computations performed on the LIMID is according to the Lazy Evaluation scheme.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:25:07 GMT" } ]
1,358,121,600,000
[ [ "Madsen", "Anders L.", "" ], [ "Nilsson", "Dennis", "" ] ]
1301.2293
Pedrito Maynard-Reid II
Pedrito Maynard-Reid II, Urszula Chajewska
Aggregating Learned Probabilistic Beliefs
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-354-361
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider the task of aggregating beliefs of severalexperts. We assume that these beliefs are represented as probabilitydistributions. We argue that the evaluation of any aggregationtechnique depends on the semantic context of this task. We propose aframework, in which we assume that nature generates samples from a`true' distribution and different experts form their beliefs based onthe subsets of the data they have a chance to observe. Naturally, theideal aggregate distribution would be the one learned from thecombined sample sets. Such a formulation leads to a natural way tomeasure the accuracy of the aggregation mechanism.We show that the well-known aggregation operator LinOP is ideallysuited for that task. We propose a LinOP-based learning algorithm,inspired by the techniques developed for Bayesian learning, whichaggregates the experts' distributions represented as Bayesiannetworks. Our preliminary experiments show that this algorithmperforms well in practice.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:25:16 GMT" } ]
1,358,121,600,000
[ [ "Maynard-Reid", "Pedrito", "II" ], [ "Chajewska", "Urszula", "" ] ]
1301.2295
Quaid Morris
Quaid Morris
Recognition Networks for Approximate Inference in BN20 Networks
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-370-377
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose using recognition networks for approximate inference inBayesian networks (BNs). A recognition network is a multilayerperception (MLP) trained to predict posterior marginals given observedevidence in a particular BN. The input to the MLP is a vector of thestates of the evidential nodes. The activity of an output unit isinterpreted as a prediction of the posterior marginal of thecorresponding variable. The MLP is trained using samples generated fromthe corresponding BN.We evaluate a recognition network that was trained to do inference ina large Bayesian network, similar in structure and complexity to theQuick Medical Reference, Decision Theoretic (QMR-DT). Our networkis a binary, two-layer, noisy-OR network containing over 4000 potentially observable nodes and over 600 unobservable, hidden nodes. Inreal medical diagnosis, most observables are unavailable, and there isa complex and unknown bias that selects which ones are provided. Weincorporate a very basic type of selection bias in our network: a knownpreference that available observables are positive rather than negative.Even this simple bias has a significant effect on the posterior. We compare the performance of our recognition network tostate-of-the-art approximate inference algorithms on a large set oftest cases. In order to evaluate the effect of our simplistic modelof the selection bias, we evaluate algorithms using a variety ofincorrectly modeled observation biases. Recognition networks performwell using both correct and incorrect observation biases.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:25:25 GMT" } ]
1,358,121,600,000
[ [ "Morris", "Quaid", "" ] ]
1301.2296
Kevin Murphy
Kevin Murphy, Yair Weiss
The Factored Frontier Algorithm for Approximate Inference in DBNs
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-378-385
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The Factored Frontier (FF) algorithm is a simple approximate inferencealgorithm for Dynamic Bayesian Networks (DBNs). It is very similar tothe fully factorized version of the Boyen-Koller (BK) algorithm, butinstead of doing an exact update at every step followed bymarginalisation (projection), it always works with factoreddistributions. Hence it can be applied to models for which the exactupdate step is intractable. We show that FF is equivalent to (oneiteration of) loopy belief propagation (LBP) on the original DBN, andthat BK is equivalent (to one iteration of) LBP on a DBN where wecluster some of the nodes. We then show empirically that byiterating, LBP can improve on the accuracy of both FF and BK. Wecompare these algorithms on two real-world DBNs: the first is a modelof a water treatment plant, and the second is a coupled HMM, used tomodel freeway traffic.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:25:29 GMT" } ]
1,358,121,600,000
[ [ "Murphy", "Kevin", "" ], [ "Weiss", "Yair", "" ] ]
1301.2297
Ann Nicholson
Ann Nicholson, Tal Boneh, Tim Wilkin, Kaye Stacey, Liz Sonenberg, Vicki Steinle
A Case Study in Knowledge Discovery and Elicitation in an Intelligent Tutoring Application
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-386-394
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Most successful Bayesian network (BN) applications to datehave been built through knowledge elicitation from experts.This is difficult and time consuming, which has lead to recentinterest in automated methods for learning BNs from data. We present a case study in the construction of a BN in anintelligent tutoring application, specifically decimal misconceptions. Wedescribe the BN construction using expert elicitation and then investigate how certainexisting automated knowledge discovery methods might support the BN knowledge engineering process.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:25:34 GMT" } ]
1,358,121,600,000
[ [ "Nicholson", "Ann", "" ], [ "Boneh", "Tal", "" ], [ "Wilkin", "Tim", "" ], [ "Stacey", "Kaye", "" ], [ "Sonenberg", "Liz", "" ], [ "Steinle", "Vicki", "" ] ]
1301.2299
James D. Park
James D. Park, Adnan Darwiche
Approximating MAP using Local Search
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-403-410
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
MAP is the problem of finding a most probable instantiation of a set of variables in a Bayesian network, given evidence. Unlike computing marginals, posteriors, and MPE (a special case of MAP), the time and space complexity of MAP is not only exponential in the network treewidth, but also in a larger parameter known as the "constrained" treewidth. In practice, this means that computing MAP can be orders of magnitude more expensive than computingposteriors or MPE. Thus, practitioners generally avoid MAP computations, resorting instead to approximating them by the most likely value for each MAP variableseparately, or by MPE.We present a method for approximating MAP using local search. This method has space complexity which is exponential onlyin the treewidth, as is the complexity of each search step. We investigate the effectiveness of different local searchmethods and several initialization strategies and compare them to otherapproximation schemes.Experimental results show that local search provides a much more accurate approximation of MAP, while requiring few search steps.Practically, this means that the complexity of local search is often exponential only in treewidth as opposed to the constrained treewidth, making approximating MAP as efficient as other computations.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:25:42 GMT" } ]
1,358,121,600,000
[ [ "Park", "James D.", "" ], [ "Darwiche", "Adnan", "" ] ]
1301.2301
Avi Pfeffer
Avi Pfeffer
Sufficiency, Separability and Temporal Probabilistic Models
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-421-428
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Suppose we are given the conditional probability of one variable given some other variables.Normally the full joint distribution over the conditioning variablesis required to determine the probability of the conditioned variable.Under what circumstances are the marginal distributions over the conditioning variables sufficient to determine the probability ofthe conditioned variable?Sufficiency in this sense is equivalent to additive separability ofthe conditional probability distribution.Such separability structure is natural and can be exploited forefficient inference.Separability has a natural generalization to conditional separability.Separability provides a precise notion of weaklyinteracting subsystems in temporal probabilistic models.Given a system that is decomposed into separable subsystems, exactmarginal probabilities over subsystems at future points in time can becomputed by propagating marginal subsystem probabilities, rather thancomplete system joint probabilities.Thus, separability can make exact prediction tractable.However, observations can break separability,so exact monitoring of dynamic systems remains hard.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:25:51 GMT" } ]
1,358,121,600,000
[ [ "Pfeffer", "Avi", "" ] ]
1301.2302
Daniel Pless
Daniel Pless, George Luger
Toward General Analysis of Recursive Probability Models
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-429-436
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
There is increasing interest within the research community in the design and use of recursive probability models. Although there still remains concern about computational complexity costs and the fact that computing exact solutions can be intractable for many nonrecursive models and impossible in the general case for recursive problems, several research groups are actively developing computational techniques for recursive stochastic languages. We have developed an extension to the traditional lambda-calculus as a framework for families of Turing complete stochastic languages. We have also developed a class of exact inference algorithms based on the traditional reductions of the lambda-calculus. We further propose that using the deBruijn notation (a lambda-calculus notation with nameless dummies) supports effective caching in such systems (caching being an essential component of efficient computation). Finally, our extension to the lambda-calculus offers a foundation and general theory for the construction of recursive stochastic modeling languages as well as promise for effective caching and efficient approximation algorithms for inference.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:25:55 GMT" } ]
1,358,121,600,000
[ [ "Pless", "Daniel", "" ], [ "Luger", "George", "" ] ]
1301.2304
Pascal Poupart
Pascal Poupart, Craig Boutilier
Vector-space Analysis of Belief-state Approximation for POMDPs
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-445-452
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose a new approach to value-directed belief state approximation for POMDPs. The value-directed model allows one to choose approximation methods for belief state monitoring that have a small impact on decision quality. Using a vector space analysis of the problem, we devise two new search procedures for selecting an approximation scheme that have much better computational properties than existing methods. Though these provide looser error bounds, we show empirically that they have a similar impact on decision quality in practice, and run up to two orders of magnitude more quickly.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:26:03 GMT" } ]
1,358,121,600,000
[ [ "Poupart", "Pascal", "" ], [ "Boutilier", "Craig", "" ] ]
1301.2305
Pascal Poupart
Pascal Poupart, Luis E. Ortiz, Craig Boutilier
Value-Directed Sampling Methods for POMDPs
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-453-461
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider the problem of approximate belief-state monitoring using particle filtering for the purposes of implementing a policy for a partially-observable Markov decision process (POMDP). While particle filtering has become a widely-used tool in AI for monitoring dynamical systems, rather scant attention has been paid to their use in the context of decision making. Assuming the existence of a value function, we derive error bounds on decision quality associated with filtering using importance sampling. We also describe an adaptive procedure that can be used to dynamically determine the number of samples required to meet specific error bounds. Empirical evidence is offered supporting this technique as a profitable means of directing sampling effort where it is needed to distinguish policies.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:26:08 GMT" } ]
1,358,121,600,000
[ [ "Poupart", "Pascal", "" ], [ "Ortiz", "Luis E.", "" ], [ "Boutilier", "Craig", "" ] ]
1301.2307
Khashayar Rohanimanesh
Khashayar Rohanimanesh, Sridhar Mahadevan
Decision-Theoretic Planning with Concurrent Temporally Extended Actions
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-472-479
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We investigate a model for planning under uncertainty with temporallyextended actions, where multiple actions can be taken concurrently at each decision epoch. Our model is based on the options framework, and combines it with factored state space models,where the set of options can be partitioned into classes that affectdisjoint state variables. We show that the set of decisionepochs for concurrent options defines a semi-Markov decisionprocess, if the underlying temporally extended actions being parallelized arerestricted to Markov options. This property allows us to use SMDPalgorithms for computing the value function over concurrentoptions. The concurrent options model allows overlapping execution ofoptions in order to achieve higher performance or in order to performa complex task. We describe a simple experiment using a navigationtask which illustrates how concurrent options results in a faster planwhen compared to the case when only one option is taken at a time.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:26:17 GMT" } ]
1,358,121,600,000
[ [ "Rohanimanesh", "Khashayar", "" ], [ "Mahadevan", "Sridhar", "" ] ]
1301.2308
Paat Rusmevichientong
Paat Rusmevichientong, Benjamin van Roy
A Tractable POMDP for a Class of Sequencing Problems
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-480-487
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider a partially observable Markov decision problem (POMDP) that models a class of sequencing problems. Although POMDPs are typically intractable, our formulation admits tractable solution. Instead of maintaining a value function over a high-dimensional set of belief states, we reduce the state space to one of smaller dimension, in which grid-based dynamic programming techniques are effective. We develop an error bound for the resulting approximation, and discuss an application of the model to a problem in targeted advertising.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:26:22 GMT" } ]
1,358,121,600,000
[ [ "Rusmevichientong", "Paat", "" ], [ "van Roy", "Benjamin", "" ] ]
1301.2312
Jin Tian
Jin Tian, Judea Pearl
Causal Discovery from Changes
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-512-521
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose a new method of discovering causal structures, based on the detection of local, spontaneous changes in the underlying data-generating model. We analyze the classes of structures that are equivalent relative to a stream of distributions produced by local changes, and devise algorithms that output graphical representations of these equivalence classes. We present experimental results, using simulated data, and examine the errors associated with detection of changes and recovery of structures.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:26:39 GMT" } ]
1,358,121,600,000
[ [ "Tian", "Jin", "" ], [ "Pearl", "Judea", "" ] ]
1301.2313
Tim Van Allen
Tim Van Allen, Russell Greiner, Peter Hooper
Bayesian Error-Bars for Belief Net Inference
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-522-529
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A Bayesian Belief Network (BN) is a model of a joint distribution over a setof n variables, with a DAG structure to represent the immediate dependenciesbetween the variables, and a set of parameters (aka CPTables) to represent thelocal conditional probabilities of a node, given each assignment to itsparents. In many situations, these parameters are themselves random variables - this may reflect the uncertainty of the domain expert, or may come from atraining sample used to estimate the parameter values. The distribution overthese "CPtable variables" induces a distribution over the response the BNwill return to any "What is Pr(H | E)?" query. This paper investigates thevariance of this response, showing first that it is asymptotically normal,then providing its mean and asymptotical variance. We then present aneffective general algorithm for computing this variance, which has the samecomplexity as simply computing the (mean value of) the response itself - ie,O(n 2^w), where n is the number of variables and w is the effective treewidth. Finally, we provide empirical evidence that this algorithm, whichincorporates assumptions and approximations, works effectively in practice,given only small samples.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:26:44 GMT" } ]
1,358,121,600,000
[ [ "Van Allen", "Tim", "" ], [ "Greiner", "Russell", "" ], [ "Hooper", "Peter", "" ] ]
1301.2314
Linda C. van der Gaag
Linda C. van der Gaag, Silja Renooij
Analysing Sensitivity Data from Probabilistic Networks
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-530-537
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
With the advance of efficient analytical methods for sensitivity analysis ofprobabilistic networks, the interest in the sensitivities revealed by real-life networks is rekindled. As the amount of data resulting from a sensitivity analysis of even a moderately-sized network is alreadyoverwhelming, methods for extracting relevant information are called for. One such methodis to study the derivative of the sensitivity functions yielded for a network's parameters. We further propose to build upon the concept of admissible deviation, that is, the extent to which a parameter can deviate from the true value without inducing a change in the most likely outcome. We illustrate these concepts by means of a sensitivity analysis of a real-life probabilistic network in oncology.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:26:48 GMT" } ]
1,358,121,600,000
[ [ "van der Gaag", "Linda C.", "" ], [ "Renooij", "Silja", "" ] ]
1301.2319
Bo Zhang
Bo Zhang, Qingsheng Cai, Jianfeng Mao, Baining Guo
Planning and Acting under Uncertainty: A New Model for Spoken Dialogue Systems
Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001)
null
null
UAI-P-2001-PG-572-579
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Uncertainty plays a central role in spoken dialogue systems. Some stochastic models like Markov decision process (MDP) are used to model the dialogue manager. But the partially observable system state and user intention hinder the natural representation of the dialogue state. MDP-based system degrades fast when uncertainty about a user's intention increases. We propose a novel dialogue model based on the partially observable Markov decision process (POMDP). We use hidden system states and user intentions as the state set, parser results and low-level information as the observation set, domain actions and dialogue repair actions as the action set. Here the low-level information is extracted from different input modals, including speech, keyboard, mouse, etc., using Bayesian networks. Because of the limitation of the exact algorithms, we focus on heuristic approximation algorithms and their applicability in POMDP for dialogue management. We also propose two methods for grid point selection in grid-based approximation algorithms.
[ { "version": "v1", "created": "Thu, 10 Jan 2013 16:27:11 GMT" } ]
1,358,121,600,000
[ [ "Zhang", "Bo", "" ], [ "Cai", "Qingsheng", "" ], [ "Mao", "Jianfeng", "" ], [ "Guo", "Baining", "" ] ]
1301.2774
Jafar Muhammadi
Jafar Muhammadi, Hamid Reza Rabiee and Abbas Hosseini
Crowd Labeling: a survey
Under consideration for publication in Knowledge and Information Systems
null
null
null
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Recently, there has been a burst in the number of research projects on human computation via crowdsourcing. Multiple choice (or labeling) questions could be referred to as a common type of problem which is solved by this approach. As an application, crowd labeling is applied to find true labels for large machine learning datasets. Since crowds are not necessarily experts, the labels they provide are rather noisy and erroneous. This challenge is usually resolved by collecting multiple labels for each sample, and then aggregating them to estimate the true label. Although the mechanism leads to high-quality labels, it is not actually cost-effective. As a result, efforts are currently made to maximize the accuracy in estimating true labels, while fixing the number of acquired labels. This paper surveys methods to aggregate redundant crowd labels in order to estimate unknown true labels. It presents a unified statistical latent model where the differences among popular methods in the field correspond to different choices for the parameters of the model. Afterwards, algorithms to make inference on these models will be surveyed. Moreover, adaptive methods which iteratively collect labels based on the previously collected labels and estimated models will be discussed. In addition, this paper compares the distinguished methods, and provides guidelines for future work required to address the current open issues.
[ { "version": "v1", "created": "Sun, 13 Jan 2013 14:12:53 GMT" }, { "version": "v2", "created": "Tue, 8 Apr 2014 05:59:49 GMT" }, { "version": "v3", "created": "Wed, 3 Sep 2014 06:37:23 GMT" } ]
1,409,788,800,000
[ [ "Muhammadi", "Jafar", "" ], [ "Rabiee", "Hamid Reza", "" ], [ "Hosseini", "Abbas", "" ] ]
1301.3832
Teresa Alsinet
Teresa Alsinet, Lluis Godo
A Complete Calculus for Possibilistic Logic Programming with Fuzzy Propositional Variables
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-1-10
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we present a propositional logic programming language for reasoning under possibilistic uncertainty and representing vague knowledge. Formulas are represented by pairs (A, c), where A is a many-valued proposition and c is value in the unit interval [0,1] which denotes a lower bound on the belief on A in terms of necessity measures. Belief states are modeled by possibility distributions on the set of all many-valued interpretations. In this framework, (i) we define a syntax and a semantics of the general underlying uncertainty logic; (ii) we provide a modus ponens-style calculus for a sublanguage of Horn-rules and we prove that it is complete for determining the maximum degree of possibilistic belief with which a fuzzy propositional variable can be entailed from a set of formulas; and finally, (iii) we show how the computation of a partial matching between fuzzy propositional variables, in terms of necessity measures for fuzzy sets, can be included in our logic programming system.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:48:38 GMT" } ]
1,358,467,200,000
[ [ "Alsinet", "Teresa", "" ], [ "Godo", "Lluis", "" ] ]
1301.3834
Ann Becker
Ann Becker, Dan Geiger, Christopher Meek
Perfect Tree-Like Markovian Distributions
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-19-23
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We show that if a strictly positive joint probability distribution for a set of binary random variables factors according to a tree, then vertex separation represents all and only the independence relations enclosed in the distribution. The same result is shown to hold also for multivariate strictly positive normal distributions. Our proof uses a new property of conditional independence that holds for these two classes of probability distributions.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:48:48 GMT" } ]
1,358,467,200,000
[ [ "Becker", "Ann", "" ], [ "Geiger", "Dan", "" ], [ "Meek", "Christopher", "" ] ]
1301.3835
Salem Benferhat
Salem Benferhat, Didier Dubois, Souhila Kaci, Henri Prade
A Principled Analysis of Merging Operations in Possibilistic Logic
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-24-31
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Possibilistic logic offers a qualitative framework for representing pieces of information associated with levels of uncertainty of priority. The fusion of multiple sources information is discussed in this setting. Different classes of merging operators are considered including conjunctive, disjunctive, reinforcement, adaptive and averaging operators. Then we propose to analyse these classes in terms of postulates. This is done by first extending the postulate for merging classical bases to the case where priorites are avaialbe.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:48:52 GMT" } ]
1,358,467,200,000
[ [ "Benferhat", "Salem", "" ], [ "Dubois", "Didier", "" ], [ "Kaci", "Souhila", "" ], [ "Prade", "Henri", "" ] ]
1301.3836
Daniel S Bernstein
Daniel S Bernstein, Shlomo Zilberstein, Neil Immerman
The Complexity of Decentralized Control of Markov Decision Processes
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-32-37
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Planning for distributed agents with partial state information is considered from a decision- theoretic perspective. We describe generalizations of both the MDP and POMDP models that allow for decentralized control. For even a small number of agents, the finite-horizon problems corresponding to both of our models are complete for nondeterministic exponential time. These complexity results illustrate a fundamental difference between centralized and decentralized control of Markov processes. In contrast to the MDP and POMDP problems, the problems we consider provably do not admit polynomial-time algorithms and most likely require doubly exponential time to solve in the worst case. We have thus provided mathematical evidence corresponding to the intuition that decentralized planning problems cannot easily be reduced to centralized problems and solved exactly using established techniques.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:48:55 GMT" } ]
1,358,467,200,000
[ [ "Bernstein", "Daniel S", "" ], [ "Zilberstein", "Shlomo", "" ], [ "Immerman", "Neil", "" ] ]
1301.3839
Craig Boutilier
Craig Boutilier
Approximately Optimal Monitoring of Plan Preconditions
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-54-62
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Monitoring plan preconditions can allow for replanning when a precondition fails, generally far in advance of the point in the plan where the precondition is relevant. However, monitoring is generally costly, and some precondition failures have a very small impact on plan quality. We formulate a model for optimal precondition monitoring, using partially-observable Markov decisions processes, and describe methods for solving this model efficitively, though approximately. Specifically, we show that the single-precondition monitoring problem is generally tractable, and the multiple-precondition monitoring policies can be efficitively approximated using single-precondition soultions.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:49:07 GMT" } ]
1,358,467,200,000
[ [ "Boutilier", "Craig", "" ] ]
1301.3841
Jian Cheng
Jian Cheng, Marek J. Druzdzel
Computational Investigation of Low-Discrepancy Sequences in Simulation Algorithms for Bayesian Networks
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-72-81
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Monte Carlo sampling has become a major vehicle for approximate inference in Bayesian networks. In this paper, we investigate a family of related simulation approaches, known collectively as quasi-Monte Carlo methods based on deterministic low-discrepancy sequences. We first outline several theoretical aspects of deterministic low-discrepancy sequences, show three examples of such sequences, and then discuss practical issues related to applying them to belief updating in Bayesian networks. We propose an algorithm for selecting direction numbers for Sobol sequence. Our experimental results show that low-discrepancy sequences (especially Sobol sequence) significantly improve the performance of simulation algorithms in Bayesian networks compared to Monte Carlo sampling.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:49:15 GMT" } ]
1,358,467,200,000
[ [ "Cheng", "Jian", "" ], [ "Druzdzel", "Marek J.", "" ] ]
1301.3842
David Maxwell Chickering
David Maxwell Chickering, David Heckerman
A Decision Theoretic Approach to Targeted Advertising
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-82-88
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A simple advertising strategy that can be used to help increase sales of a product is to mail out special offers to selected potential customers. Because there is a cost associated with sending each offer, the optimal mailing strategy depends on both the benefit obtained from a purchase and how the offer affects the buying behavior of the customers. In this paper, we describe two methods for partitioning the potential customers into groups, and show how to perform a simple cost-benefit analysis to decide which, if any, of the groups should be targeted. In particular, we consider two decision-tree learning algorithms. The first is an "off the shelf" algorithm used to model the probability that groups of customers will buy the product. The second is a new algorithm that is similar to the first, except that for each group, it explicitly models the probability of purchase under the two mailing scenarios: (1) the mail is sent to members of that group and (2) the mail is not sent to members of that group. Using data from a real-world advertising experiment, we compare the algorithms to each other and to a naive mail-to-all strategy.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:49:19 GMT" } ]
1,358,467,200,000
[ [ "Chickering", "David Maxwell", "" ], [ "Heckerman", "David", "" ] ]
1301.3844
Gregory F. Cooper
Gregory F. Cooper
A Bayesian Method for Causal Modeling and Discovery Under Selection
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-98-106
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper describes a Bayesian method for learning causal networks using samples that were selected in a non-random manner from a population of interest. Examples of data obtained by non-random sampling include convenience samples and case-control data in which a fixed number of samples with and without some condition is collected; such data are not uncommon. The paper describes a method for combining data under selection with prior beliefs in order to derive a posterior probability for a model of the causal processes that are generating the data in the population of interest. The priors include beliefs about the nature of the non-random sampling procedure. Although exact application of the method would be computationally intractable for most realistic datasets, efficient special-case and approximation methods are discussed. Finally, the paper describes how to combine learning under selection with previous methods for learning from observational and experimental data that are obtained on random samples of the population of interest. The net result is a Bayesian methodology that supports causal modeling and discovery from a rich mixture of different types of data.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:49:26 GMT" } ]
1,358,467,200,000
[ [ "Cooper", "Gregory F.", "" ] ]
1301.3845
Fabio Gagliardi Cozman
Fabio Gagliardi Cozman
Separation Properties of Sets of Probability Measures
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-107-114
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
This paper analyzes independence concepts for sets of probability measures associated with directed acyclic graphs. The paper shows that epistemic independence and the standard Markov condition violate desirable separation properties. The adoption of a contraction condition leads to d-separation but still fails to guarantee a belief separation property. To overcome this unsatisfactory situation, a strong Markov condition is proposed, based on epistemic independence. The main result is that the strong Markov condition leads to strong independence and does enforce separation properties; this result implies that (1) separation properties of Bayesian networks do extend to epistemic independence and sets of probability measures, and (2) strong independence has a clear justification based on epistemic independence and the strong Markov condition.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:49:30 GMT" } ]
1,358,467,200,000
[ [ "Cozman", "Fabio Gagliardi", "" ] ]
1301.3846
James Cussens
James Cussens
Stochastic Logic Programs: Sampling, Inference and Applications
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-115-122
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Algorithms for exact and approximate inference in stochastic logic programs (SLPs) are presented, based respectively, on variable elimination and importance sampling. We then show how SLPs can be used to represent prior distributions for machine learning, using (i) logic programs and (ii) Bayes net structures as examples. Drawing on existing work in statistics, we apply the Metropolis-Hasting algorithm to construct a Markov chain which samples from the posterior distribution. A Prolog implementation for this is described. We also discuss the possibility of constructing explicit representations of the posterior.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:49:34 GMT" } ]
1,358,467,200,000
[ [ "Cussens", "James", "" ] ]
1301.3847
Adnan Darwiche
Adnan Darwiche
A Differential Approach to Inference in Bayesian Networks
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-123-132
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present a new approach for inference in Bayesian networks, which is mainly based on partial differentiation. According to this approach, one compiles a Bayesian network into a multivariate polynomial and then computes the partial derivatives of this polynomial with respect to each variable. We show that once such derivatives are made available, one can compute in constant-time answers to a large class of probabilistic queries, which are central to classical inference, parameter estimation, model validation and sensitivity analysis. We present a number of complexity results relating to the compilation of such polynomials and to the computation of their partial derivatives. We argue that the combined simplicity, comprehensiveness and computational complexity of the presented framework is unique among existing frameworks for inference in Bayesian networks.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:49:38 GMT" } ]
1,358,467,200,000
[ [ "Darwiche", "Adnan", "" ] ]
1301.3848
Adnan Darwiche
Adnan Darwiche
Any-Space Probabilistic Inference
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-133-142
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We have recently introduced an any-space algorithm for exact inference in Bayesian networks, called Recursive Conditioning, RC, which allows one to trade space with time at increments of X-bytes, where X is the number of bytes needed to cache a floating point number. In this paper, we present three key extensions of RC. First, we modify the algorithm so it applies to more general factorization of probability distributions, including (but not limited to) Bayesian network factorizations. Second, we present a forgetting mechanism which reduces the space requirements of RC considerably and then compare such requirmenets with those of variable elimination on a number of realistic networks, showing orders of magnitude improvements in certain cases. Third, we present a version of RC for computing maximum a posteriori hypotheses (MAP), which turns out to be the first MAP algorithm allowing a smooth time-space tradeoff. A key advantage of presented MAP algorithm is that it does not have to start from scratch each time a new query is presented, but can reuse some of its computations across multiple queries, leading to significant savings in ceratain cases.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:49:42 GMT" } ]
1,358,467,200,000
[ [ "Darwiche", "Adnan", "" ] ]
1301.3855
Nir Friedman
Nir Friedman, Dan Geiger, Noam Lotner
Likelihood Computations Using Value Abstractions
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-192-200
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we use evidence-specific value abstraction for speeding Bayesian networks inference. This is done by grouping variable values and treating the combined values as a single entity. As we show, such abstractions can exploit regularities in conditional probability distributions and also the specific values of observed variables. To formally justify value abstraction, we define the notion of safe value abstraction and devise inference algorithms that use it to reduce the cost of inference. Our procedure is particularly useful for learning complex networks with many hidden variables. In such cases, repeated likelihood computations are required for EM or other parameter optimization techniques. Since these computations are repeated with respect to the same evidence set, our methods can provide significant speedup to the learning procedure. We demonstrate the algorithm on genetic linkage problems where the use of value abstraction sometimes differentiates between a feasible and non-feasible solution.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:50:10 GMT" } ]
1,358,467,200,000
[ [ "Friedman", "Nir", "" ], [ "Geiger", "Dan", "" ], [ "Lotner", "Noam", "" ] ]
1301.3858
Phan H. Giang
Phan H. Giang, Prakash P. Shenoy
A Qualitative Linear Utility Theory for Spohn's Theory of Epistemic Beliefs
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-220-229
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we formulate a qualitative "linear" utility theory for lotteries in which uncertainty is expressed qualitatively using a Spohnian disbelief function. We argue that a rational decision maker facing an uncertain decision problem in which the uncertainty is expressed qualitatively should behave so as to maximize "qualitative expected utility." Our axiomatization of the qualitative utility is similar to the axiomatization developed by von Neumann and Morgenstern for probabilistic lotteries. We compare our results with other recent results in qualitative decision making.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:50:22 GMT" } ]
1,358,467,200,000
[ [ "Giang", "Phan H.", "" ], [ "Shenoy", "Prakash P.", "" ] ]
1301.3859
Peter J Gorniak
Peter J. Gorniak, David L. Poole
Building a Stochastic Dynamic Model of Application Use
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-230-237
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Many intelligent user interfaces employ application and user models to determine the user's preferences, goals and likely future actions. Such models require application analysis, adaptation and expansion. Building and maintaining such models adds a substantial amount of time and labour to the application development cycle. We present a system that observes the interface of an unmodified application and records users' interactions with the application. From a history of such observations we build a coarse state space of observed interface states and actions between them. To refine the space, we hypothesize sub-states based upon the histories that led users to a given state. We evaluate the information gain of possible state splits, varying the length of the histories considered in such splits. In this way, we automatically produce a stochastic dynamic model of the application and of how it is used. To evaluate our approach, we present models derived from real-world application usage data.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:50:26 GMT" } ]
1,358,467,200,000
[ [ "Gorniak", "Peter J.", "" ], [ "Poole", "David L.", "" ] ]
1301.3860
Peter D Grunwald
Peter D. Grunwald
Maximum Entropy and the Glasses You Are Looking Through
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-238-246
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We give an interpretation of the Maximum Entropy (MaxEnt) Principle in game-theoretic terms. Based on this interpretation, we make a formal distinction between different ways of {em applying/} Maximum Entropy distributions. MaxEnt has frequently been criticized on the grounds that it leads to highly representation dependent results. Our distinction allows us to avoid this problem in many cases.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:50:30 GMT" } ]
1,358,467,200,000
[ [ "Grunwald", "Peter D.", "" ] ]
1301.3864
Michael C. Horsch
Michael C. Horsch, Bill Havens
Probabilistic Arc Consistency: A Connection between Constraint Reasoning and Probabilistic Reasoning
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-282-290
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We document a connection between constraint reasoning and probabilistic reasoning. We present an algorithm, called {em probabilistic arc consistency}, which is both a generalization of a well known algorithm for arc consistency used in constraint reasoning, and a specialization of the belief updating algorithm for singly-connected networks. Our algorithm is exact for singly- connected constraint problems, but can work well as an approximation for arbitrary problems. We briefly discuss some empirical results, and related methods.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:50:46 GMT" } ]
1,358,467,200,000
[ [ "Horsch", "Michael C.", "" ], [ "Havens", "Bill", "" ] ]
1301.3866
Radim Jirousek
Radim Jirousek
Marginalization in Composed Probabilistic Models
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-301-308
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Composition of low-dimensional distributions, whose foundations were laid in the papaer published in the Proceeding of UAI'97 (Jirousek 1997), appeared to be an alternative apparatus to describe multidimensional probabilistic models. In contrast to Graphical Markov Models, which define multidomensinoal distributions in a declarative way, this approach is rather procedural. Ordering of low-dimensional distributions into a proper sequence fully defines the resepctive computational procedure; therefore, a stury of different type of generating sequences is one fo the central problems in this field. Thus, it appears that an important role is played by special sequences that are called perfect. Their main characterization theorems are presetned in this paper. However, the main result of this paper is a solution to the problem of margnialization for general sequences. The main theorem describes a way to obtain a generating sequence that defines the model corresponding to the marginal of the distribution defined by an arbitrary genearting sequence. From this theorem the reader can see to what extent these comutations are local; i.e., the sequence consists of marginal distributions whose computation must be made by summing up over the values of the variable eliminated (the paper deals with finite model).
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:50:54 GMT" } ]
1,358,467,200,000
[ [ "Jirousek", "Radim", "" ] ]
1301.3868
Uffe Kj{\ae}rulff
Uffe Kj{\ae}rulff, Linda C. van der Gaag
Making Sensitivity Analysis Computationally Efficient
Appears in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence (UAI2000)
null
null
UAI-P-2000-PG-317-325
cs.AI
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
To investigate the robustness of the output probabilities of a Bayesian network, a sensitivity analysis can be performed. A one-way sensitivity analysis establishes, for each of the probability parameters of a network, a function expressing a posterior marginal probability of interest in terms of the parameter. Current methods for computing the coefficients in such a function rely on a large number of network evaluations. In this paper, we present a method that requires just a single outward propagation in a junction tree for establishing the coefficients in the functions for all possible parameters; in addition, an inward propagation is required for processing evidence. Conversely, the method requires a single outward propagation for computing the coefficients in the functions expressing all possible posterior marginals in terms of a single parameter. We extend these results to an n-way sensitivity analysis in which sets of parameters are studied.
[ { "version": "v1", "created": "Wed, 16 Jan 2013 15:51:02 GMT" } ]
1,358,467,200,000
[ [ "Kjærulff", "Uffe", "" ], [ "van der Gaag", "Linda C.", "" ] ]