{ "paper_id": "P01-1031", "header": { "generated_with": "S2ORC 1.0.0", "date_generated": "2023-01-19T09:30:14.055192Z" }, "title": "Resolving Ellipsis in Clarification", "authors": [ { "first": "Jonathan", "middle": [], "last": "Ginzburg", "suffix": "", "affiliation": {}, "email": "ginzburg@dcs.kcl.ac.uk" }, { "first": "Robin", "middle": [], "last": "Cooper", "suffix": "", "affiliation": { "laboratory": "", "institution": "G\u00f6teborg University", "location": { "postBox": "Box 200", "postCode": "405 30", "settlement": "G\u00f6teborg", "country": "Sweden" } }, "email": "cooper@ling.gu.se" } ], "year": "", "venue": null, "identifiers": {}, "abstract": "We offer a computational analysis of the resolution of ellipsis in certain cases of dialogue clarification. We show that this goes beyond standard techniques used in anaphora and ellipsis resolution and requires operations on highly structured, linguistically heterogeneous representations. We characterize these operations and the representations on which they operate. We offer an analysis couched in a version of Head-Driven Phrase Structure Grammar combined with a theory of information states (IS) in dialogue. We sketch an algorithm for the process of utterance integration in ISs which leads to grounding or clarification. 1 An anonymous ACL reviewer proposed to us that all CE could be analyzed in terms of a single reading along the lines of \"I thought I heard you say Bo, and I don't know why you would do so?\". 2 Closely related to this issue is the issue of what other readings/understandings CE exhibits. We defer discussion of the latter issue to (Purver et al., 2001), which provides a detailed analysis of the frequency of CEs and their understandings among clarification utterances in the British National Corpus (BNC). 3 This confirms our (non-instrumentally tested) impression that these understandings are not on the whole disambiguated intonationally. All our CE data from the BNC was found using SCoRE, Matt Purver's dialogue oriented BNC search engine (Purver, 2001).", "pdf_parse": { "paper_id": "P01-1031", "_pdf_hash": "", "abstract": [ { "text": "We offer a computational analysis of the resolution of ellipsis in certain cases of dialogue clarification. We show that this goes beyond standard techniques used in anaphora and ellipsis resolution and requires operations on highly structured, linguistically heterogeneous representations. We characterize these operations and the representations on which they operate. We offer an analysis couched in a version of Head-Driven Phrase Structure Grammar combined with a theory of information states (IS) in dialogue. We sketch an algorithm for the process of utterance integration in ISs which leads to grounding or clarification. 1 An anonymous ACL reviewer proposed to us that all CE could be analyzed in terms of a single reading along the lines of \"I thought I heard you say Bo, and I don't know why you would do so?\". 2 Closely related to this issue is the issue of what other readings/understandings CE exhibits. We defer discussion of the latter issue to (Purver et al., 2001), which provides a detailed analysis of the frequency of CEs and their understandings among clarification utterances in the British National Corpus (BNC). 3 This confirms our (non-instrumentally tested) impression that these understandings are not on the whole disambiguated intonationally. All our CE data from the BNC was found using SCoRE, Matt Purver's dialogue oriented BNC search engine (Purver, 2001).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Abstract", "sec_num": null } ], "body_text": [ { "text": "Clarification ellipsis (CE), nonsentential elliptical queries such as (1a(i),(ii)) are commonplace in human conversation. Two common readings/understandings of CE are exemplified in (1b,c): the clausal reading is commonly used simply to confirm the content of a particular subutterance. The main function of the constituent reading is to elicit an alternative description or ostension to the content (referent or predicate etc) intended by the original speaker of the reprised subutterance.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "(1) a. A: Did Bo finagle a raise? B: (i) Bo?/ (ii) finagle?", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "b. Clausal reading: Are you asking if BO (of all people) finagled a raise/Bo FI-NAGLED a raise (of all actions) c.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "Constituent reading: Who is Bo?/What does it mean to finagle? The issue of whether CE involves an ambiguity or is simply vague is an important one. 1 2 Clearly, pragmatic reasoning plays an important role in understanding CEs. Some considerations do, nonetheless, favour the existence of an ambiguity. First, the BNC provides numerous examples of misunderstandings concerning CE interpretation, 3 where a speaker intends one reading, is misunderstood, and clarifies his original interpretation:", "cite_spans": [ { "start": 395, "end": 396, "text": "3", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "(2) a. A: ... you always had er er say every foot he had with a piece of spunyarn in the wire/B: Spunyarn?/A: Spunyarn, yes/B: What's spunyarn? b. A: Have a laugh and joke with Dick./ B: Dick?/A: Have a laugh and joke with Dick./B: Who's Dick?", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "More crucially, the clausal and constituent readings involve distinct syntactic and phonological parallelism conditions. The constituent reading seems to actually require phonological identity. With the resolution associated with clausal readings, there is no such requirement. However, partial syntactic parallelism does obtain: an XP used to clarify an antecedent sub-utterance", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "\u00a1 \u00a3 \u00a2 must match \u00a1 \u00a3 \u00a2", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "categorially, though there is no requirement of phonological identity:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "(3) a. A: I phoned him. B: him? / #he? b. A: Did he adore the book. B: adore? / #adored? c. A: We're leaving? B: You?", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "We are used to systems that will confirm the user's utterances by repeating part of them. These presuppose no sophisticated linguistic analysis. However, it is not usual for a system to be able to process CEs produced by the user. It would be a great advantage in negotiative dialogues, where, for example, the system and the user might be discussing several options and the system may make alternative suggestions, for a system to be able to recognize and interpret a CE. Consider the following (constructed) dialogue in the routeplanning domain:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "(4) Sys: Would you like to make that trip via Malvern? User: Malvern?", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "At this point the system has to consider a number of possible intepretations for the user's utterance all of which involve recognizing that this is a clarification request concerning the system's last utterance.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "Appropriate responses might be (5a-c); the system should definitely not say (5d), as it might if it does not recognize that the user is trying to clarify its previous utterance.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "(5) a. Yes, Malvern b. Malvern -M-A-L-V-E-R-N c.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "Going via Malvern is the quickest route d. So, you would like to make that trip via Malvern instead of Malvern?", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "In this paper we examine the interpretation of CEs. CE is a singularly complex ellipsis/anaphoric phenomenon which cannot be handled by standard techniques such as first order unification (as anaphora often is) or by higher order unification (HOU) on logical forms (see e.g. (Pulman, 1997) ). For a start, in order to capture the syntactic and phonological parallelism exemplified in (3), logical forms are simply insufficient. Moreover, although an HOU account could, given a theory of dialogue that structures context appropriately, generate the clausal reading, the constituent reading cannot be so generated. Clark (e.g. (Clark, 1996) ) initiated work on the grounding of an utterance (for computational and formal work see e.g. (Traum, 1994; Poesio and Traum, 1997) ). However, existing work, while spelling out in great detail what updates arise in an IS as a result of grounding, do not offer a characterization of the clarification possibilities spawned by a given utterance. A sketch of such a characterization is provided in this paper. On the basis of this we offer an analysis of CE, integrated into a large existing grammar framework, Head-Driven Phrase Structure Grammar (HPSG) (specifically the version developed in (Ginzburg and Sag, 2000) ). We start by informally describing the grounding/clarification processes and the representations on which they operate. We then provide the requisite background on HPSG and on the KOS framework (Ginzburg, 1996; Bohlin et al., 1999) , in which our analysis of ISs is couched. We sketch an algorithm for the process of utterance integration which leads to grounding or clarification. Finally, we formalize the operations which underpin clarification and sketch a grammatical analysis of CE.", "cite_spans": [ { "start": 275, "end": 289, "text": "(Pulman, 1997)", "ref_id": "BIBREF12" }, { "start": 625, "end": 638, "text": "(Clark, 1996)", "ref_id": "BIBREF1" }, { "start": 733, "end": 746, "text": "(Traum, 1994;", "ref_id": "BIBREF15" }, { "start": 747, "end": 770, "text": "Poesio and Traum, 1997)", "ref_id": "BIBREF10" }, { "start": 1231, "end": 1255, "text": "(Ginzburg and Sag, 2000)", "ref_id": "BIBREF3" }, { "start": 1452, "end": 1468, "text": "(Ginzburg, 1996;", "ref_id": "BIBREF5" }, { "start": 1469, "end": 1489, "text": "Bohlin et al., 1999)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "We start by offering an informal description of how an utterance \u00a1 such as (6) can get grounded or spawn a clarification by an addressee B: (6) A: Did Bo leave?", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Utterance Representation: grounding and clarification", "sec_num": "2" }, { "text": "A is attempting to convey to B her question whether the property she has referred to with her utterance of leave holds of the person she has referred to with the name Bo. B is required to try and find values for these references. Finding values is, with an important caveat, a necessary condition for B to ground A's utterance, thereby signalling that its content has been integrated in B's IS. 4 Modelling this condition for successful grounding provides one obvious constraint on the representation of utterance types: such a representation must involve a function from or \u00a4 abstract over a set of certain parameters (the contextual parameters) to contents. This much is familiar already from early work on context dependence by (Montague, 1974) ? In such a case B needs to do at least the following: (1) perform a partial update of the existing context with the successfully processed components of the utterance (2) pose a clarification question that involves reference to the subutterance u\u00a6 from which \u00a5 emanates. Since the original speaker, A, can coherently integrate a clarification question once she hears it, it follows that, for a given utterance, there is a predictable range of \u00a7 partial updates + consequent clarification questions\u00a8. These we take to be specified by a set of coercion operations on utterance representations. 5 Indeed we assume that a component of dialogue competence is knowledge of these coercion operations.", "cite_spans": [ { "start": 731, "end": 747, "text": "(Montague, 1974)", "ref_id": "BIBREF9" }, { "start": 1341, "end": 1342, "text": "5", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Utterance Representation: grounding and clarification", "sec_num": "2" }, { "text": "CE gives us some indication concerning both the input and required output of these operations. One such operation, which we will refer to as parameter identification, essentially involves as output a question paraphrasable as what is the intended reference of sub-utterance u\u00a6 ?. The partially updated context in which such a clarification takes place is such that simply repeating the segmental phonology of u\u00a6 using rising intonation enables that question to be expressed. Another existent coercion operation is one which we will refer to as parameter focussing. This involves a (partially updated) context in which the issue under discussion is a question that arises by instantiating all contextual parameters except for \u00a5 and abstracting over", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Utterance Representation: grounding and clarification", "sec_num": "2" }, { "text": ". In such a context, one 4 The caveat is, of course, that the necessity is goal driven. Relative to certain goals, one might decide simply to existentially quantify the problematic referent. For this operation on meanings see (Cooper, 1998) . We cannot enter here into a discussion of how to integrate the view developed here in a plan based view of understanding, but see (Ginzburg, (forthcoming) ) for this.", "cite_spans": [ { "start": 25, "end": 26, "text": "4", "ref_id": null }, { "start": 226, "end": 240, "text": "(Cooper, 1998)", "ref_id": "BIBREF2" }, { "start": 373, "end": 397, "text": "(Ginzburg, (forthcoming)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "\u00a5", "sec_num": null }, { "text": "5 The term coercion operation is inspired by work on utterance representation within a type theoretic framework reported in (Cooper, 1998) .", "cite_spans": [ { "start": 124, "end": 138, "text": "(Cooper, 1998)", "ref_id": "BIBREF2" } ], "ref_spans": [], "eq_spans": [], "section": "\u00a5", "sec_num": null }, { "text": "can confirm that \u00a5 gets the value B suspects it has by uttering with rising intonation any apparently co-referential phrase whose syntactic category is identical to \u00a1 \u00a3 \u00a2 's. From this discussion, it becomes clear that coercion operations (and by extension the grounding process) cannot be defined simply on meanings. Rather, given the syntactic and phonological parallelism encoded in clarification contexts, these operations need to be defined on representations that encode in parallel for each subutterance down to the word level phonological, syntactic, semantic, and contextual information. With some minor modifications, signs as conceived in HPSG are exactly such a representational format and, hence, we will use them to define coercion operations. 6 More precisely, given that an addressee might not be able to come up with a unique or a complete parse, due to lexical ignorance or a noisy environment, we need to utilize some 'underspecified' entity (see e.g. (Milward, 2000) ). For simplicity we will use descriptions of signs. An example of the format for signs we employ is given in (7): 7 6 We make two minor modifications to the version of HPSG described in (Ginzburg and Sag, 2000) ). First, we revamp the existing treatment of the feature C-INDICES. This will now encode the entire inventory of contextual parameters of an utterance (proper names, deictic pronouns, indexicals) not merely information about speaker/hearer/utterancetime, as standardly. Indeed, in principle, relation names should also be included, since they vary with context and are subject to clarification as well. Such a step involves a significant change to how argument roles are handled in existing HPSG. Hence, we do not make such a move here. This modification of C-INDICES will allow signs to play a role akin to the role associated with 'meanings', i.e. to function as abstracts with roles that need to be instantiated. The second modification we make concerns the encoding of phrasal constituency. Standardly, the feature DTRS is used to encode immediate phrasal constituency. To facilitate statement of coercion operations, we need access to all phrasal constituentsgiven that a contextual parameter emanating from deeply embedding constituents are as clarifiable as immediate constituents. We posit a set valued feature CONSTIT(UENT)S whose value is the set of all constituents immediate or otherwise of a given sign (Cf. the mother-daughter predicates used in (Gregory and Lappin, 1999) .) In fact, having posited CONSTITS one could eliminate DTRS: this by making the value of CONSTITS be a set of sets whose first level elements are the immediate constituents. For current purposes, we stick with tradition and tolerate the redundancy of both DTRS and CONSTITS.", "cite_spans": [ { "start": 971, "end": 986, "text": "(Milward, 2000)", "ref_id": "BIBREF8" }, { "start": 1104, "end": 1105, "text": "6", "ref_id": null }, { "start": 1174, "end": 1198, "text": "(Ginzburg and Sag, 2000)", "ref_id": "BIBREF3" }, { "start": 2460, "end": 2486, "text": "(Gregory and Lappin, 1999)", "ref_id": "BIBREF7" } ], "ref_spans": [], "eq_spans": [], "section": "\u00a5", "sec_num": null }, { "text": "7 Within the phrasal type system of (Ginzburg and Sag, 2000) root-cl constitutes the 'start' symbol of the grammar. In particular, phrases of this type have as their content an illocutionary operator embedding the appropriate semantic", "cite_spans": [ { "start": 36, "end": 60, "text": "(Ginzburg and Sag, 2000)", "ref_id": "BIBREF3" } ], "ref_spans": [], "eq_spans": [], "section": "\u00a5", "sec_num": null }, { "text": "(7) \u00a9 root-cl PHON did bo leave CAT V[+fin] C-INDICES , , , i,j CONT \u00a9 ASK-REL ASKER i ASKED j MSG-ARG \u00a9 question PARAMS PROP S OA \u00a9 leave-rel AGT TIME ! ! CTXT B CKGRD \" utt-time( ), precede( , ), named(bo)( ) # CONSTITS $ % & PHON Did' , ( & PHON Bo' , ) & PHON leave' , 0 & PHON Did Bo leave' 2 1", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\u00a5", "sec_num": null }, { "text": "Before we can explain how these representations can feature in dialogue reasoning and the resolution of CE, we need to sketch briefly the approach to dialogue ellipsis that we assume.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\u00a5", "sec_num": null }, { "text": "We adopt the situation semantics based theory of dialogue context developed in the KOS framework (Ginzburg, 1996; Ginzburg, (forthcoming) ; Bohlin et al., 1999) . The common ground component of ISs is assumed to be structured as follows: 8", "cite_spans": [ { "start": 97, "end": 113, "text": "(Ginzburg, 1996;", "ref_id": "BIBREF5" }, { "start": 114, "end": 137, "text": "Ginzburg, (forthcoming)", "ref_id": "BIBREF6" }, { "start": 140, "end": 160, "text": "Bohlin et al., 1999)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Contextual evolution and ellipsis", "sec_num": "3" }, { "text": "(8) \u00a9 FACTS set of facts LATEST-MOVE (illocutionary) fact QUD p.o.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Contextual evolution and ellipsis", "sec_num": "3" }, { "text": "In (Ginzburg and Sag, 2000) this framework is integrated into HPSG (Pollard and Sag, 1994) ; (Ginzburg and Sag, 2000) define two new attributes within the CONTEXT (CTXT) feature structure: Maximal Question Under Discussion (MAX-QUD), whose value is of sort question; 9 object (an assertion embedding a proposition, a query embedding a question etc.). Here and throughout we omit various features (e.g. STORE, SLASH etc that have no bearing on current issues wherever possible.", "cite_spans": [ { "start": 3, "end": 27, "text": "(Ginzburg and Sag, 2000)", "ref_id": "BIBREF3" }, { "start": 67, "end": 90, "text": "(Pollard and Sag, 1994)", "ref_id": "BIBREF11" }, { "start": 93, "end": 117, "text": "(Ginzburg and Sag, 2000)", "ref_id": "BIBREF3" } ], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "8 Here FACTS corresponds to the set of commonly accepted assumptions; QUD('questions under discussion') is a set consisting of the currently discussable questions, partially ordered by 3 ('takes conversational precedence'); LATEST-MOVE represents information about the content and structure of the most recent accepted illocutionary move.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "9 Questions are represented as semantic objects comprising a set of parameters-empty for a polar question-and a and Salient Utterance (SAL-UTT), whose value is a set (singleton or empty) of elements of type sign. In information structure terms, SAL-UTT can be thought of as a means of underspecifying the subsequent focal (sub)utterance or as a potential parallel element. MAX-QUD corresponds to the ground of the dialogue at a given point. Since SAL-UTT is a sign, it enables one to encode syntactic categorial parallelism and, as we will see below, also phonological parallelism. SAL-UTT is computed as the (sub)utterance associated with the role bearing widest scope within MAX-QUD. 10 Below, we will show how to extend this account of parallelism to clarification queries.", "cite_spans": [ { "start": 686, "end": 688, "text": "10", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "To account for elliptical constructions such as short answers and sluicing, Ginzburg and Sag posit a phrasal type headed-fragment-phrase (hdfrag-ph)-a subtype of hd-only-ph-governed by the constraint in (9). The various fragments analyzed here will be subtypes of hd-frag-ph or else will contain such a phrase as a head daughter. 11 (9)", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "\u00a9 HEAD v CTXT S AL-UTT 4 CAT CONT I NDEX 5 HD-DTR 6 CAT & HEAD nominal' CONT I NDEX 7 !", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "This constraint coindexes the head daughter with the SAL-UTT. This will have the effect of 'unifying in' the content of the former into a contextually provided content. A subtype of hd-fragph relevant to the current paper is (decl-frag-cl)also a subtype of decl-cl-used to analyze short answers:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "proposition. This is the feature structure counterpart of the", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "8 -abstract 8 @ 9 B A D C E C F C G 9 H C F C F CI . 10", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "For Wh-questions, SAL-UTT is the wh-phrase associated with the PARAMS set of the question; otherwise, its possible values are either the empty set or the utterance associated with the widest scoping quantifier in In the (Ginzburg and Sag, 2000) version of HPSG information about phrases is encoded by cross-classifying them in a multi-dimensional type hierarchy. Phrases are classified not only in terms of their phrase structure schema or X-bar type, but also with respect to a further informational dimension of CLAUSALITY. Clauses are divided into inter alia declarative clauses (decl-cl), which denote propositions, and interrogative clauses (inter-cl) denoting questions. Each maximal phrasal type inherits from both these dimensions. This classification allows specification of systematic correlations between clausal construction types and types of semantic content. (10)", "cite_spans": [ { "start": 220, "end": 244, "text": "(Ginzburg and Sag, 2000)", "ref_id": "BIBREF3" } ], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "\u00a9 STORE P R Q CONT \u00a9 proposition SIT SOA 4 QUANTS order( P @ S ) T U NUCL ( 5 ! MAX-QUD \u00a9 question PARAMS neset PROP \u00a9 proposition SIT SOA 4 QUANTS U NUCL ( 5 ! ! HD-DTR S TORE P @ S V P R Q set(param)", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "The content of this phrasal type is a proposition: whereas in most headed clauses the content is entirely (or primarily) derived from the head daughter, here it is constructed for the most part from the contextually salient question. This provides the concerned situation and the nucleus, whereas if the fragment is (or contains) a quantifier, that quantifier must outscope any quantifiers already present in the contextually salient question.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "set of questions", "sec_num": null }, { "text": "Before we turn to formalizing the coercion operations and describing CE, we need to explain how on our view utterances get integrated in an agent's IS. The basic protocol we assume is given in (11) below. 12 (11) Utterance processing protocol (3) React to content(u) according to querying/assertion protocols.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": "(4) If successful, X", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": "is removed from PENDING (b) Else:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": "Repeat from stage (a) with MAX-QUD and SAL-UTT obtaining the various values of coef", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": "A 2 g h I i q p s r u t w v x X y h x F p s B t X @", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": ", where g is the sign associated with LATEST-MOVE and coef is one of the available coercion operations;", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": "(c) Else: make an utterance appropriate for a context such that MAX-QUD and SAL-UTT get values according to the specification in coef", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": "A X R b d I", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": ", where coef is one of the available coercion operations.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": "The protocol involves the assumption that an agent always initially tries to integrate an utterance by assuming it constitutes an adjacency pair with the existing LATEST-MOVE. If this route is blocked somehow, because the current utterance cannot be grounded or the putative resolution leads to incoherence, only then does she try to repair by assuming the previous utterance is a clarification generated in accordance with the existing coercion operations. If that too fails, then, she herself generates a clarification. Thus, the prediction made by this protocol is that A will tend to initially interpret (12(2)) as a response to her question, not as a clarification: 12A(1): Who do you think is the only person that admires Mary? B(2): Mary?", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Integrating Utterances in Information States", "sec_num": "4" }, { "text": "We now turn to formalizing the coercion operations we specified informally in section 2. The first operation we define is parameter focussing:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "(13) parameter focussing f : \u00a9 root-cl CTXT-INDICES C F C F C f C F C C CONSTITS C E C F C & CONT f ' C C F C CONTENT ! \u00a9 CONTENT M SG-ARG 4 question PROP 5 SAL-UTT MAX-QUD \u00a9 q uestion PARAMS f PROP ! !", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "This is to be understood as follows: given an utterance (whose associated sign is one) which satisfies the specification in the LHS of the rule, a CP may respond with any utterance which satisfies the specification in the RHS of the rule. 13 More specifically, the input of the rules singles out a contextual parameter \u00a5 , which is the content of an element of the daughter set of the utterance 2 . Intuitively, \u00a5 is a parameter whose value is problematic or lacking. The sub-utterance 2 is specified to constitute the value of the feature SAL-UTT associated with the context of the clarification utterance \u00a1", "cite_spans": [ { "start": 239, "end": 241, "text": "13", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": ". The descriptive content of \u00a1 is a question, any question whose open proposition 3 (given in terms of the feature PROP) is identical to the (uninstantiated) content of the clarified utterance. MAX-QUD associated with the clarification is fully specified as a question whose open proposition is 3 and whose PARAMS set consists of the 'problematic' parameter \u00a5 . We can exemplify the effect of parameter focussing with respect to clarifying an utterance of (7). The output this yields, when applied to Bo's index 1 , is the partial specification in (14). Such an utterance will have as its MAX-QUD a question cq paraphrasable as who , named Bo, are you asking if t left, whereas its SAL-UTT is the sub-utterance of Bo. The content is underspecified: Given space constraints, we restrict ourselves to explaining how the clausal CE, (15c), gets analyzed. This involves direct application of the type decl-frag-cl discussed above for short answers. The QUD-maximality of cq allows us to analyze the fragment as a 'short answer' to cq , using the type bare-decl-cl. And out of the proposition which emerges courtesy of bare-decl-cl a (polar) question is constructed using the type dir-is-intcl. 14 16S", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "(14) \u00a9 CONT M SG-ARG question PROP SAL-UTT d M AX-QUD \u00a9 question PARAM S Q PROP S OA \u00a9 ASK-REL ASKER i ASKED j M SG-ARG \u00a9 question PARAM", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "\u00a9 dir-is-int-cl CONT \u00a9 question PARAMS PROP \u00a9 ask-rel ASKER i ASKED j \u00a9 question PARAMS PROP S OA \u00a9 leave-rel AGT TIME ! ! ! S \u00a9 decl-frag-cl CONT CTXT \u00a9 MAX-QUD \u00a9 question PARAMS & INDEX ' PROP ! SAL-UTT 4 CAT 0 CONT I NDEX 5 ! 4 CAT 0 NP CONT I NDEX 5 Bo", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "The second coercion operation we discussed previously is parameter identification: for a given problematic contextual parameter its output is a partial specification for a sign whose content and MAX-QUD involve a question querying the content of that utterance parameter:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "(17) parameter identification f : \u00a9 root-cl CTXT-INDICES C F C F C f C F C C CONSTITS C F C C & CONT f ' C F C F C ! C C F C ! \u00a9 CONTENT M SG-ARG 4 question PROP 5 SAL-UTT MAX-QUD \u00a9 question PARAMS & INDEX % ' PROP \u00a9 SOA \u00a9 content-rel SIGN CONT % ! !", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "To exemplify: when this operation is applied to (7), it will yield as output the partial specification in (18):", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "(18) \u00a9 CONT M SG-ARG 4 question PROP ) 5 SAL-UTT ( \u00a9 PHON bo CAT NP CONT I NDEX f CTXT B CKGRD named(Bo)( f ) ! MAX-QUD \u00a9 question PARAMS & INDEX f ' PROP ) \u00a9 SOA \u00a9 content-rel SIGN ( CONT f ! !", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "This specification will allows for clarification questions such as the following:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "(19)", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "a. Who do you mean BO? b. WHO? (= who is Bo) c. Bo? (= who is Bo) We restrict attention to (19c), which is the most interesting but also tricky example. The tricky part arises from the fact that in a case such as this, in contrast to all previous examples, the fragment does not contribute its conventional content to the clausal content. Rather, as we suggested earlier, the semantic function of the fragment is merely to serve as an anaphoric element to the phonologically identical to-be-clarified sub-utterance. The content derives entirely from MAX-QUD. Such utterances can still be analyzed as subtypes of head-frag-ph, though not as decl-frag-cl, the short-answer/reprise sluice phrasal type we have been appealing to extensively. Thus, we posit constit(uent)-clar(ification)-int-cl, a new phrasal subtype of head-frag-ph and of inter-cl which encapsulates the two idiosyncratic facets of such utterances, namely the phonological parallelism and the max-qud/content identity: In this paper we offered an analysis of the types of representations needed to analyze CE, the requisite operations thereon, and how these update ISs during grounding and clarification. Systems which respond appropriately to CEs in general will need a great deal of background knowledge. Even choosing among the responses in (5) might be a pretty knowledge intensive business. However, there are some clear strategies that might be pursued. For example, if Malvern has been discussed previously in the dialogue and understood then (5a,b) would not be appropriate responses. In order to be able to build dialogue systems that can handle even some restricted aspects of CEs we need to understand more about what the possible interpretations are and this is what we have attempted to do in this paper. We are currently working on a system which integrates SHARDS (see , a system which processes dialogue ellipses) with GoDiS (see (Bohlin et al., 1999) , a dialogue system developed using TRINDIKIT, which makes use of ISs modelled on those suggested in the KOS framework. Our aim in the near future is to incorporate simple aspects of negotiative dialogue including CEs in a GoDiS-like system employing SHARDS.", "cite_spans": [ { "start": 1910, "end": 1931, "text": "(Bohlin et al., 1999)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Sign Coercion and an Analysis of CE", "sec_num": "5" }, { "text": "In this protocol, PENDING is a stack whose elements are (unintegrated) utterances.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "", "sec_num": null }, { "text": "The fact that both the LHS and the RHS of the rule are of type root-cl ensures that the rule applies only to signs associated with complete utterances.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "", "sec_num": null }, { "text": "The phrasal type dir-is-int-cl which constitutes the type of the mother node in (16) is a type that inter alia enables a polar question to be built from a head daughter whose content is propositional. See(Ginzburg and Sag, 2000) for details.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "", "sec_num": null } ], "back_matter": [ { "text": "For very useful discussion and comments we would like to thank Pat Healey, Howard Gregory, Shalom Lappin, Dimitra Kolliakou, David Milward, Matt Purver and three anonymous ACL reviewers. We would also like to thank Matt Purver for help in using SCoRE. Earlier versions of this work were presented at colloquia at ITRI, Brighton, Queen Mary and Westfield College, London, and at the Computer Lab, Cambridge. The research described here is funded by grant number R00022269 from the Economic and Social Research Council of the United Kingdom, by INDI (Information Exchange in Dialogue), Riksbankens Jubileumsfond 1997-0134, and by grant number GR/R04942/01 from the Engineering and Physical Sciences Research Council of the United Kingdom.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Acknowledgements", "sec_num": null } ], "bib_entries": { "BIBREF0": { "ref_id": "b0", "title": "Elisabet Engdahl, and Staffan Larsson. 1999. Information states and dialogue move engines", "authors": [ { "first": "Peter", "middle": [], "last": "Bohlin", "suffix": "" }, { "first": "Robin", "middle": [], "last": "Cooper", "suffix": "" } ], "year": null, "venue": "Gothenburg Papers in Computational Linguistics", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Peter Bohlin, Robin Cooper, Elisabet Engdahl, and Staffan Larsson. 1999. 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