{ "paper_id": "C92-1046", "header": { "generated_with": "S2ORC 1.0.0", "date_generated": "2023-01-19T12:34:25.999080Z" }, "title": "On Representing the Temporal Structure of a Natural Language Text*", "authors": [ { "first": "Kurt", "middle": [], "last": "Eberle", "suffix": "", "affiliation": { "laboratory": "", "institution": "Institut fiir Maschinelle Sprachverarbeitung Universit\u00a3t Stuttgart Azenbergstrafle", "location": { "postCode": "12 7000", "settlement": "Stuttgart" } }, "email": "kurt@adler.philosophie.uni-stuttgart.de" } ], "year": "", "venue": null, "identifiers": {}, "abstract": "A proposal to deal with tenses in the framework of Discourse Representation Theory is presented, ms it has been implemented for a fragment at the IMS for the project LILOG. It is based on the theory of tenses of H. Kamp and Ch. Rohrer. The system uses tile tense and aspect information, the information about the temporal discourse structure of tile preceding text stored in a specific list of possible reference times, and background knowledge. These types of information interact in order to choose a suited temporal anchor for the event of a new sentence. With respect to extended texts, choosing the right reference time for a new event is a problem which has been largely neglected in the literature.", "pdf_parse": { "paper_id": "C92-1046", "_pdf_hash": "", "abstract": [ { "text": "A proposal to deal with tenses in the framework of Discourse Representation Theory is presented, ms it has been implemented for a fragment at the IMS for the project LILOG. It is based on the theory of tenses of H. Kamp and Ch. Rohrer. The system uses tile tense and aspect information, the information about the temporal discourse structure of tile preceding text stored in a specific list of possible reference times, and background knowledge. These types of information interact in order to choose a suited temporal anchor for the event of a new sentence. With respect to extended texts, choosing the right reference time for a new event is a problem which has been largely neglected in the literature.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Abstract", "sec_num": null } ], "body_text": [ { "text": "In Reichenbach (1947) the tenses are analyzed into different orderlngs of the relevant temporal parameters which are: the time of the event talked about, the speech time (time of utterance) and the reference time. Simple past, for instance, identifies event-and reference-time, which are both before the speech time. In the case of past perfect the event time precedes the reference time which precedes the speech time.", "cite_spans": [ { "start": 3, "end": 21, "text": "Reichenbach (1947)", "ref_id": "BIBREF17" } ], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "Kanlp attd Rohrer (1983, 1985) were led by textphenomena to split up the Reichenbachian reference time into two contextually given coordinates: the reference time (in the narrow sense) and the temporal perspective time.", "cite_spans": [ { "start": 18, "end": 24, "text": "(1983,", "ref_id": null }, { "start": 25, "end": 30, "text": "1985)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "(1) Harry handed the book about giraffes to Jane (el).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "In (1) , the events e2 -e5 are ordered consecutively, *This research has been done in the context of LILOG. Thanks on this way to the members of the LILOG-researeh group of IBM for helpfull comments and especially for having made the integration of the suggested system in the LILOGprototype possible. each taking its predecessor as reference time, with the exception that the context does not provide au event which precedes e2 and which, therefore, could play the role of reference time with respect to e2. Tile whole sequence e2 -es is seen from a vantage point in the past, el, which, therefore, plays the role of perspective time with regard to the structural integration of e2 -c5. The perspective from which e 1 and es are seen is the speech tinle, e t serves as reference time for c~. In the approach of Kamp and Rohrer the role that the reference time plays in Reichenbach's system is taken over by the perspective time with respect to the meaning of the tenses in single sentence discourses: The meaning (one of tile meanings) of past perfect is that the event tittle precedes the perspective time which precedes the speech time. The meaning of simple past is that the event time precedes the speech time which coincides with tile perspective time. However, in addition to a system like Reichenbach's there is another parameter which comes exclusively from the text, the reference time proper, which is part of tile impact of the tenses on the temporal reconstruction of a narrative, titus completing the sentential meaning of the tenses by a textual aspect. Here, the idea, that we take over from Kamp and P~ohrer , is that in a sequence of simple past sentences introducing events (not states) normally the event of a new senteuce follows the reference time which is provided by the event of the preceding sentence within the sequence. By transposition the same should hold for sequences of past perfect sentences. Here, the perspective is shifted from the speech time to a (contextually given) point in the past. There is an additional feature however with respect to temporal parameters. Adverbials can provide a location time for events and states. For instance, in (1), the 1o. cation time of e2 is the time pointed to by two hours ago.", "cite_spans": [ { "start": 3, "end": 6, "text": "(1)", "ref_id": "BIBREF0" }, { "start": 1608, "end": 1624, "text": "Kamp and P~ohrer", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Two hours ago he had descovered it in Alfred's bookshop (e2). He had bought it (es), had inserted a dedication (e4) and had it wrapped up (e~). Jane took the book with a smile (e~)", "sec_num": null }, { "text": "On the basis of the Reichenbachian approach using three temporal parameters the problem of integrating a new event in the event structure of tile preceding text has been attacked by Hinrichs (1986) , Partee(1984) and others. More independant of this approach are suggestions made by Moens and Steedmalt (1988} aatd by Webber(1988).", "cite_spans": [ { "start": 182, "end": 197, "text": "Hinrichs (1986)", "ref_id": "BIBREF7" }, { "start": 200, "end": 212, "text": "Partee(1984)", "ref_id": "BIBREF16" } ], "ref_spans": [], "eq_spans": [], "section": "Two hours ago he had descovered it in Alfred's bookshop (e2). He had bought it (es), had inserted a dedication (e4) and had it wrapped up (e~). Jane took the book with a smile (e~)", "sec_num": null }, { "text": "Since we tllink tltat it correct anMysis of narratives eamlot do without a fine grained distinction between the roles played by temporal anchors, our aplu'oach uses the coordinates suggested by Kamp and Ptnllrer. Such coordinates arc stored in a structured list., called T-list, which rettects the discourse structure of the preceding text. The l)rol)lem of choosing tim right anchor for the new event froln the preceding text is largely neglected in thc literature. Very often there, tile preceding text consists of only one sentence or tile problem is restricted to thc intra-sentential one presented by temporal conjunctions. How do we decide in (1) that the reference time for ca is not tile earlier introduced el, but e2 and that the reference tinle for e(t is not the most recent reference time es, but el': hi our system we use tile structure of the T-list aluong other things to get a hierachy of the topicality of tile rcfi~'renee times. This is very ch)se to tim idea of accessibility in Discourse Rel)resentatiou Theory (Kamp (1981) ) and to tile notion of focus in the work of Grosz and Sidner (1985) . Ill or(ler to tackle tile task of event-integration, which we call \"temporM resolution\" -slaking Mhtsion to the very similar probteln of the NP-resohltion, where anaphoric links for the c~me of nominals have to be established -we struct~.lrc the T-list along the lines of different discourse rclations such ms continuation, elaboration, flashback etc. Fla-sllback, for instance, holds in the example above between e 1 alld e 2 and between el alld e3. Tile relation between e2 and c3 is contimmtion. As we will set' ill the section after next, often, fi'om the purely linguistic l)oint of view timre are alternatives with resl)ect to the decision about the discourse relation which directs the iutegration of a new event or state.", "cite_spans": [ { "start": 194, "end": 202, "text": "Kamp and", "ref_id": null }, { "start": 1031, "end": 1043, "text": "(Kamp (1981)", "ref_id": "BIBREF8" }, { "start": 1089, "end": 1112, "text": "Grosz and Sidner (1985)", "ref_id": "BIBREF6" } ], "ref_spans": [], "eq_spans": [], "section": "Two hours ago he had descovered it in Alfred's bookshop (e2). He had bought it (es), had inserted a dedication (e4) and had it wrapped up (e~). Jane took the book with a smile (e~)", "sec_num": null }, { "text": "Ill our system, the criteria to decide about the relevant discourse relation are provided by tile tense fi)rlus of the reference event(s) and of the new event respectively, by tile existence aairl the elmracteristics of temporal adverbiMs, by the ,aspect of the events -is it all event proper or a state -and by internal se.luantic properties of the events whicil are made explicit by means t)f rules stored ill the background knowledge. Of course, in addition, tile hierarchically structured T-list inflnences tile cltoice and helps to update the system correctly, where updating means adding a new telnporal condition to the representation of the text and a(lding a new refereltee time to tim T-list at, a specific l)htee.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Two hours ago he had descovered it in Alfred's bookshop (e2). He had bought it (es), had inserted a dedication (e4) and had it wrapped up (e~). Jane took the book with a smile (e~)", "sec_num": null }, { "text": "In tlm next section we will briefly introduce tile kind of discourse representation structures that we use. Then we wilt say something about the discourse relations deidt with and we l)resent tile syntax of tile T-list. After tltat we sketch the relevant background knowledge and finally, we give some of the resolution rules of tilt' system.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Two hours ago he had descovered it in Alfred's bookshop (e2). He had bought it (es), had inserted a dedication (e4) and had it wrapped up (e~). Jane took the book with a smile (e~)", "sec_num": null }, { "text": "The structuring of tile T-list extents a suggestion of Eberle and Kasper (1989) and comprises elenlents of a proposal by Reyle (1986) .", "cite_spans": [ { "start": 55, "end": 79, "text": "Eberle and Kasper (1989)", "ref_id": "BIBREF5" }, { "start": 121, "end": 133, "text": "Reyle (1986)", "ref_id": "BIBREF18" } ], "ref_spans": [], "eq_spans": [], "section": "Two hours ago he had descovered it in Alfred's bookshop (e2). He had bought it (es), had inserted a dedication (e4) and had it wrapped up (e~). Jane took the book with a smile (e~)", "sec_num": null }, { "text": "Tile algorithm suggested is part of the LILOGprototype witich is used for text understanding. In Affl]~s DE COLING-92, NANTES, 23-28 AOrdr 1992 particular it uses kaowledge provided by tile knowledge base and the inference component of the prototype.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Two hours ago he had descovered it in Alfred's bookshop (e2). He had bought it (es), had inserted a dedication (e4) and had it wrapped up (e~). Jane took the book with a smile (e~)", "sec_num": null }, { "text": "Witidn tile framework of Discourse Representation Theory (DRT) (Kamp(1981)) a Discourse Representation Structure (D1LS) is a pair < U,K > consisting of a set U of discourse referents (DRFs) and a met K of conditions. DRSs are interpreted modeltheoretically. DRT uses a variant of tim Davidsonian method of talking about events: timy are treated as a kind of objects.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "DR;F and Events", "sec_num": "2" }, { "text": "In LILOG we use DRSs for text representiLtions. But we deviate front the cla.~sicM Dl~F-style in using one-placc event predicates and thematic roles instead of n-place ew;nt predicates. A second difference is given ]W the fact that in L1LOG DllSs come with all indcx. The index is the list of reference tinles available with respect to the DRS ill question. For a simple sentence it will bc a list consisting only of one element -the DRF of the event introduced -for a text it will lie a COmlllcx list, tit(: T-list.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "DR;F and Events", "sec_num": "2" }, { "text": "So, for instance, the LIL()G-DILS for cominy o]x can be illustrated i~s follows:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "DR;F and Events", "sec_num": "2" }, { "text": "a(le~tt(e) = x", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "DR;F and Events", "sec_num": "2" }, { "text": "For the ])ITS to be valid there must exist an embedding function which nmps e onto an event of the model structure such that e satisfies tile conditions as described ill the I)RS.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "DR;F and Events", "sec_num": "2" }, { "text": "It is clear that the idea about tile order of events introduced by sequences of sentences that wc have sketched in the introduction is an oversilnpfification.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "Iu the folh)wing we will restrict ourselves to the tenses prevailing in narrativcs, silnple past and past perfect, and to only some of the text pllenomena related to these tenses (as we have done ill tile LILOG ilnl)lelnentation with respect to tile German counterparts of these tenses).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "}3csi(les tile disl:ourse relations used ill CXalnple (1), i.e. tl~shback and continuation, there are at least two nlore, which we call elabo~vltlon and backgTound.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "Conlpare the two fi)]lowing exalllples:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "(2) Mouday Hans went to Par~s. Tuesday he met Gabt.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "(3) Monday Hans went to Paris. At the border he had some trouble.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "(2) dcscril)es a continuation. This can lie deduced from the characteristics of the location times.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "In contrast to that, (3) describes an elaboration. We call the relation between a new event e2 and its reference event el an elaboration, if e2 describes et on a nmre fine-grained level (which gives rise to the temporal condition of inclusion (C_) between the new event and tile reference event within the representation of the text).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "In 3the relation of elaboration can be deduced only if there is some input from the knowledge base equipping the resolution component with facts about journeys to foreign countries. Notice that, here, the temporal inclusion is due to the hommnorphic local inclusion of tile border into the path of the travel. This illustrates that an intelligent temporal resolutimt component cannot do without having access to local reasoning.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "Now compare the following pair of examples, taken from Dowty (1986) and from Hinrichs (1986) respectively: (4) John entered the president's office. The clock on the wall ticked loudly.", "cite_spans": [ { "start": 55, "end": 67, "text": "Dowty (1986)", "ref_id": "BIBREF3" }, { "start": 77, "end": 92, "text": "Hinrichs (1986)", "ref_id": "BIBREF7" } ], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "(5) Jameson entered the room, shut the door carefully and switched off the hght. It was pitch-dark around hint because the venetian blinds were closed.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "hi both (4) and (5) the last sentence introduces not all event proper, but a state. As widely accepted, the normal case of relating a new state e2 to an existing reference event el seems to be that of inelusiml (e, C_ e2). l However, as exaalples like (5) make clear, tills default can be overwritten. Here ton, it seems that backgrmmd knowledge gives the decisive indication about when the default has to be upset.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "We call the discourse relation of (4) background and that of (5) causally introduced background. For cases like (5) we introduce tile new state e~ a.s following the actual reference event el (el -< e2) and as including a dummy reference time t (t C e:) with respect to which e2 introduces a backgrouud, ht the filrther course of processing the text, t has to be instautiated by a new event which is understood as following el.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "The T-list makes use of these discourse relations a-s structuring elements. For instance, processing the samlfle text (6), which integrates tile text phenomena reflected by the examples (1) -(4), should result in a representation which has as index the T-list ( Ill (7) the structure of (6) is stored in the following way: el, c2, sis, el 1, el2 (the leaving of Paris, the going to Frankfort, the entering tile bar, the ordering of beer and the lighting the cigarette) on tile one hand and ea,eo, e0 (tile stoppiug, the opening of the boot, the failure of the officers) on the other form continuation chains (tied up in the picture by --). The second of these chains elaborates an event of the first, e2, tile transition to Prankfort (el/\\). e4 and e~ serve as background to ea, cla is the background of e12 (bg/\\). Finally, the continuation chain c7 -ea is a flashback seen from the perspective es.", "cite_spans": [ { "start": 260, "end": 261, "text": "(", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "We define tile accessibility of all event as reference event in such a way that, having processed the whole text, the only accessible event will be elz, whereas, in the case of having processed the text till the integration of es, the accessible events will be es, es and e2 (with decreasing prominettce). In this situation es is the so called actual reference event. When integrating a new sentence, one will try to expand the node represented by the actual referent first. But, finally, what level has to be chosen and what kind of anchoring has to be stored in the next step is decided by the system rules. So, for instance, in the case of (6), by purely linguistic reasons, ea cannot be related to tile actual reference event e8, because there is a tense switch from past perfect to simple past between es and es which indicates the termination of the flashback. This results in tile re-initialization of the level ttle flashback started from as the level providing the new actual referent. In the case of (6) this is cs which is a member of an elaboration. Actual elaborations may be terminated by knowledge indicating that expanding the structure at the actual level is not plausible or even not possible. In this case the system will try to relate the new event with respect to tile (accessible) events of higher levels of the elaboration hierarchy. Since, with respect to (6), eg is compatible with e2 the system has no reason to terminate the level marked by e0. We think that the data confirm the concept of a hierarchy of reference events as used in the system. The exact defiuition of the accessible reference events of a T-list resides in the definition of the specific access-functions for T-lists that we sketch in section 5. 2", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "In fact, ill tile LILOG implementation, tile items of the index, i.e. of the. T-list, do not consist of the pure events. They are terms with different slots filled hy the relevant temporal information such ms tile tense form which introduces the corresponding event, the ,xspect, the actual speech tittle etc. Skiplfing such technical details, the simplified syntax of the T-list is the following: ", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Discourse Relations", "sec_num": "3" }, { "text": "Of course, there are other discourse relations ~ those mentioned. Especially, if one tries to analyse the structure of texts on a more fine-grained level than the purely temporal one, the relations described are not sufficient, others like explanation, contrast etc. are needed, s For lack of space, here, we can nothing say about these. The relations described are those 2Anchoring new evetlts to non-accessible reference events clearly is possible, provided there is additional information to motivate this clmice, such as, for instance, definite descriptions using event nomlnalizations in order to establish ccreferentiallty, But, at present, such possibilities are not implemented.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ell", "sec_num": null }, { "text": "3 Partly for other purposes discourse or rhetorical relations are tlsed, for instance~ in Grosz and Sidner(1985}, Thompson and Mann (1987}. dealt with ill tile LILOG system.", "cite_spans": [ { "start": 90, "end": 99, "text": "Grosz and", "ref_id": "BIBREF6" }, { "start": 100, "end": 126, "text": "Sidner(1985}, Thompson and", "ref_id": null }, { "start": 127, "end": 139, "text": "Mann (1987}.", "ref_id": "BIBREF20" } ], "ref_spans": [], "eq_spans": [], "section": "ell", "sec_num": null }, { "text": "The LILOG knowledge base provides us with a sort hierarchy for discourse referents which is related with respect to events to tile classification given in Vendler(1967) . This sort hierarchy is used as one of several information packages within the temporal resolution. With respect to the hierarchy we mainly use calendar knowledge and incompatibilty-statements about event types. For instance, all event introduced with the location time 1987 (or with subintervals of 1987) cannot overlap with an event with location time 1988. Exactly the same is true when the new event has an event type which is incompatible with the type of the reference event. A SWIMMING-event is incompatible with a WRITING-event if tile relevant therustic roles are the same, i.e., here, the agent-role. Of course, when fornlulating such incompatibilities one tries to make use of the sort hierarchy. One will define the incompatibility for very general sorts (if possible) so that it is inherited by subsorts.", "cite_spans": [ { "start": 155, "end": 168, "text": "Vendler(1967)", "ref_id": "BIBREF21" } ], "ref_spans": [], "eq_spans": [], "section": "Background Knowledge", "sec_num": "4" }, { "text": "Knowledge of this kind is hard information so to speak. In addition to this, the system uses default knowledge about event types which is similar to what ", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Background Knowledge", "sec_num": "4" }, { "text": "The construction of tile seulantic represeutation for a discourse proceeds in several stages. I shall skip here the steps leading to the DRS of a sentence. But it has to be stressed that tile result of sentence processing is not a completed DRS. There may be variables which have to be instantiated in the process of integrating the sentence-DRS into the text-DRS.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Temporal Resolution", "sec_num": "5" }, { "text": "The sentence-DRS is understood as the input of the aspect-calculus of the prototype which has to contpute the aspect of the events of the DRS. Therefore it uses tile inform~ttion provided by the thematic roles. The starting point is the aspect-entry for the verb in the lexicon. It can be overwritten by specific role information and morphological information with regard to aspect. For the sake of simplicity in the following we assume that there are just two contrasting aspects corresponding to the main sorts of the upper structure of the event sort hierarchy, the heterogeneous events proper (ev) and the honmgeneous states (st). The aspect calculus used is based on ideas fi'om Kritka (1987) 2So, for Peter wrote a book we will get the aspect value ev, whereas for Peter wrote books we will get st. For the example (6) we get that e4, es, el3 are states, the rest will be analyzed as events proper. After tile computation of the aspect we come up with an indexed DRS its descrihed iu the second and third section with the value of the aspect feature instantiated.", "cite_spans": [ { "start": 684, "end": 697, "text": "Kritka (1987)", "ref_id": "BIBREF12" } ], "ref_spans": [], "eq_spans": [], "section": "Temporal Resolution", "sec_num": "5" }, { "text": "Within the process of anchoring we use several access-functions with respect to the T-list. Among other things these are act-tel(T-list) which gives us the most topicalized item in the list, the actual", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Temporal Resolution", "sec_num": "5" }, { "text": "which givo us the points elaborations and flashbacks containing E start from. It has to be stressed that reference events have to be events proper. They caunot be states. The actual referent is the first element of the stack, provided that this element does not contMn fl~hback-or elaboration-embcddings. If it does we start the recursivc call of the search procedure with respect to the first of these embedded lists, tense{El, aspect (El, and tp(E) give us the valnes of tile tense and aspect features (sp, ppf, ev, st: simple past, past perfect, event and state) and the temporal perspective from which E is seen.", "cite_spans": [ { "start": 436, "end": 450, "text": "(El, and tp(E)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "referent, el-embedder( T-list, E), fb-embedder( T-list,E)", "sec_num": null }, { "text": "In order to decide the anchoring of new events, the rules of the system make use of three filters: (F1) tile tense/aspect filter which decides whether a particular discourse relation is possible with respect to tense and aspect, (F2) the \"consistency\" filter, which decides whether tile choice of a particular discourse relation is logically compatible with the information of the preceding text against the background of tile information from the inference component (this consists mainly of testing sort subsumptions ill the context of teml)oral incompatibilities between calendar units and event sorts), and (F3) the evidence filter which tries to support the relation tested by means of rules like (9) and (10) .", "cite_spans": [ { "start": 710, "end": 714, "text": "(10)", "ref_id": "BIBREF9" } ], "ref_spans": [], "eq_spans": [], "section": "referent, el-embedder( T-list, E), fb-embedder( T-list,E)", "sec_num": null }, { "text": "To illustrate the system we restrict ourselves to some simple eases (compare figure 1) . We suppose that the new sentence introduces just one event anti we only sketch simplified versions of tile rules for continuation, 1.), for elaboration, 2.), for flashback, 4 For a detailed description of the calculus refer to Eberle {1991}.", "cite_spans": [], "ref_spans": [ { "start": 77, "end": 86, "text": "figure 1)", "ref_id": "FIGREF1" } ], "eq_spans": [], "section": "referent, el-embedder( T-list, E), fb-embedder( T-list,E)", "sec_num": null }, { "text": "3.), for causally introduced background, 4.), for background, 5.), for termination of elaborations, 6.), and for the termination of flashbacks, 7.). We skip rules which deal with specific subcases of these relations. For instance, we skip rules which deal with dummy referents t introduced by the causal background and rules which allow for more precise temporal localizations of tile new events. We use rewrite rules which depict the amalgamation of a sentence DRS with a text DRS. Evidence for a particular relation X can be inferred, if there exists an event sort P which is more general than the event description from DRSs with respect to tile event sort hierarchy, such that tile knowledge base (KB) together with the representation of the l)receding text (DRS,) predicts an event e auf type P temporally related to e,.~y in a way significant for X, and that KB, DRS, do not entail the corresponding statement with respect to the competing relations of X. Formally, for instance with respect to X=\"eontinuation\", X is evident, if for P with Ve (ORS s[es/e] ---* P(e)), we can infer that 3e (P(e) A e,~j\" -< el, but neither that ~e (P(e)AeCe,.~l)nor3e", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "referent, el-embedder( T-list, E), fb-embedder( T-list,E)", "sec_num": null }, { "text": "(P(e)Ae7): {6) Early in the morning John entered a bar near the mess tower in Frankfort (elo), ordered a beer (el1) and lighted a cigarette (el2). He was happy (eta). (7) /\\ /\\ / el \\ / bg \\ / \\ / \\ / \\ e13 e3 ....... e6 .... e9 /\\ /\\ / bg \\ / :fb \\ e4 , aS e7 , e8", "text": "John left Paris by the Porte de 5 ~ Cloud late in the evening (el). He went to Frankfort (e2). At the border he was stopped (e3). It was pretty dark (eJ. Only a .few lights were burning (es). He had to open hz.~ boot (es). In Paris he had bought five cartons of e:garettes (e7) and had hidden them in the car (es). The customs officers missed them (eg}.IThis parallels, for instance, the insights ofPartee(1984), H inrichs( 1986l,Kamp and Rohrer(1985) and others. el .... s2 .... el0 --ell --el2", "num": null } } } }