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<Paper uid="E95-1033">
  <Title>ParseTalk about Sentenceand Text-Level Anaphora</Title>
  <Section position="2" start_page="0" end_page="237" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> This paper treats the resolution of anaphora within the framework of Parse Talk, a dependency-oriented grammar model that incorporates strict lexicalization, head-orientation (based on valency specifications), feature unification, and inheritance among lexicalized grammar specifications (Br6ker et al., 1994; Hahn et al., 1994). The results we present rest upon two major assumptions: 1. As many forms of anaphors (e.g., nominal and pronominal anaphors) occur within sentence boundaries (so-called intra-sentential or sentence anaphora) and beyond (intersentential or text anaphora), adequate theories of anaphora should allow the formulation of grammatical regularities for both types using a common set of grammatical primitives.</Paragraph>
    <Paragraph position="1"> 2. Anaphora are only one, yet very prominent phenomenon that yields textual cohesion in discourse. Adequate grammars should therefore also be easily extensible to cover non-anaphoric text phenomena (e.g., coherence relations, rhetorical predicates), which provide for additional levels of text (macro) structure, with descriptions stated at the same level of theoretical sophistication as for anaphora.</Paragraph>
    <Paragraph position="2"> First, we will briefly compare our approach with work done in the context of government-binding (GB) grammar and discourse representation the: ory (DRT). As we conceive it, binding theory as developed within the GB framework (Chomsky, 1981; Kuno, 1987) offers one of the most sophisticated approaches for treating anaphora at the sentence level of description. This has also been recognized by advocates of competing grammar formalisms, who have elaborated on GB's binding principles (cf., e.g., Pollard and Sag (1992) within the context of HPSG, whose treatment is nevertheless restricted to reflexive pronouns). Interestingly enough, when faced with some crucial linguistic phenomena, such as topicalization, GB must assume rather complex movement operations in order to cope with the data in a satisfactory manner. Things get even more complicated when languages with relatively free word order, such as German, are taken into account. Finally, considering the case of text anaphora, binding theory has nothing to offer at all.</Paragraph>
    <Paragraph position="3"> Another strong alternative for considering anaphora constitutes the framework of DRT (Kamp and Reyle, 1993). Its development can be considered a landmark in the model-theoretic semantic analysis of various forms of quantified sentences, conditionals, and anaphorically linked multi-sentential discourse. At this level of description, DRT is clearly superior to GB. On the other hand, its lack of an equally thorough treatment of complex syntactic constructions makes it inferior to GB. These deficits are no wonder, since DRT is not committed to any particular syntactic theory, and thus cannot place strict enough syntactic constraints on the admissible constituent structures. Focusing on the text analysis potential of DRT, its complex machinery might work in a satisfactory way for several well-studied forms of anaphora, but it necessarily fails if various non-anaphoric text phenomena need to be interpreted. This is particularly true of conceptually-rooted and pragmatically driven inferences necessary to build up textual macro structures in terms of coherence relations (Hobbs, 1982) or rhetorical structures (Mann and Thompson, 1988). This shortcoming is simply due to the fact that DRT is basically a semantic theory, not a comprehensive model for text understanding; it lacks any systematic connec- null tion to comprehensive reasoning systems covering the conceptual knowledge and specific problem-solving models underlying the chosen domain.</Paragraph>
    <Paragraph position="4"> Summing up, DRT is fairly restricted both with respect to the incorporation of powerful syntactic constraints at the sentence level and its extension to the level of (non-anaphoric) text macro structures. GB, on the other hand, is strong with respect to the specification of binding conditions at the sentence level, but offers no opportunity at all to extend its analytic scope beyond that sentential level. We claim, however, that the dependency-based grammar model underlying ParseTalk 1. covers intra-sentential anaphora at the same level of descriptive adequacy as current GB, although it provides less complex representation structures than GB analyses; these structures are nevertheless expressive enough to capture the relevant distinctions, 2. does not exhibit an increasing level of structural complexity when faced with crucial linguistic phenomena which cause considerable problems for current GB theory, 3. goes beyond GB in that it allows the treatment of anaphora at the text level of description within the same grammar formalism as is used for sentence level anaphora, and, 4. goes beyond the anaphora-centered treatment of text structure characteristic of the DRT approach in that it already accounts for the resolution of text-level ellipsis (sometimes also referred to as functional anaphora, cf. Hahn and Strube (1995)) and the interpretation of text macro structures (a preliminary study is presented in Hahn (1992)).</Paragraph>
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