Logical Structure and Discourse Anaphora Resolution

Working within the Dynamic "Quantifier Logic (DQL) framework (van den Berg 1992, 1996a,b), we claim in this paper that in every language the translation into a logical language will be such that the preference ordering of possible discourse referents for an anaphor in a sentence can be explained in terms of the scopal order of the exp _re~Lslons in the antecedent that introduce the discourse referents. Since the scope of terms is derived from arguments independent of any discourse theory, our account explal~ discour~ anaphora resolution in terms of general principles of utterance semantics, from whichthe predictions of centering theory follow. When comb'med with the powerful discourse structural framework of the Linguistic Discourse Model (Polanyi (1985, 1986, 1988, 1996) Potanyi and Scha (1984), Scha and Polanyi (1988), Prfist, H., tL Scha and M. tLvan den Berg, 1994; Po~u~, L. and M. H. van den Berg 1996; van den Berg, M. H. 1996b), we provide a uni6ed account of di~ourse anaphora resolution. 1 I n t r o d u c t i o n In thl. paper, we use a semantic theory based on Dynamic Quantifier Logic (van den Berg 1992,1998a,b) to present an approach to discom~ anaphora resolution under the Linguistic DL~ourse Model (Polanyi (1985, 1986, 1988, 1996) Pohmyi and Scha (1984), Scha and Pclawfi (1988), Prfmt, H., I t Scha and M. H. van den Berg, 1994; P o ~ q ~ L. and M. IL van den Berg 1996; van den Berg, M. H. 1996b). Our treatment integrates the imights of the Center~g framework (Jmbi audK,,h1979, 1981; Grosz et~l. 1983, 1986, 1995; Gundel 1998; Walker et.al. 1998b) into a -n~Sed theory of discourse level structufa/and semantic relations. In our account, discourse level aaaphora resolution effects fall out of a general theory of discourse quantification. Scope orderinge in the logical representa t ion o f the antecedent u t t e rance result in d|fferences in " The authors dedkate this paper to the memory of Megumi Kameyama (1953-1999), a dedicated researcher and a very dear friend. accessibility for potent ia l re ferents in a t a rge t u t t e rance . No additional c~ntering mechanisms are required, the centering predictions follow from this theory. Our treatment is universal: explanations of relative coherence do not depend on conventions that might differ in different languages. Furthermore, we provide a treatment for the resolution of multiple anaphors, resulting from a range of possible antecedents including plurals and multiple antecedents. The approach to discourse anaph°ra resolution we take in this paper integrates a rigorous formal semantic machinery within a theory Of discourse strtlcture. Before giving a detailed account of our treatmeat of di~murse reference resolution, we would llke to address explicitly some of the positions towards rdereace resolution and discour~ ~mcture which inform our work. 1.1 Theoret ical and Methodological Considerat ions To begin with, we should state explicitly that our enterprise is a semantic one~ we are interested in devetoping and implemen "ring a formalization capable of ._,~'amln~ a con-ect interpretation to each utterance in a discourse. In this, we are fully committed to the Dynamic Semantics enterprise (Kamp 1981, H~m 1982, Groenendijk and Stokhof, 1990, 1991, Cider~ i . 1992, van den Berg 1991, Kamp and Reyle 1993, Asher 1993, van den Berg 1998). Except in so far as it is provably necessary, we are not concerned with psychological L~sues of how human language users p r o ~ discourse nor with what human beings intend when they use language to commuIlicate with one another. Our aim is to build machinery applicable to all genres and all modes of comm~nLication. Thus we can not assume that a discourse is n e c ~ x l l y uco. hereat" and that our goal is to provide an account of why that is so, nor can we assume that all discourse iswritten or spoken or.occurs in a task context where the demands or reasonable expectations of a~ external activity are available to guide parsing and interpretation.