Anaphora and Discourse Structure

We argue in this paper that many common adverbial phrases generally taken to signal a discourse relation between syntactically connected units within discourse structure, instead work anaphorically to contribute relational meaning, with only indirect dependence on discourse structure. This allows a simpler discourse structure to provide scaffolding for compositional semantics, and reveals multiple ways in which the relational meaning conveyed by adverbial connectives can interact with that associated with discourse structure. We conclude by sketching out a lexicalised grammar for discourse that facilitates discourse interpretation as a product of compositional rules, anaphor resolution and inference.Comment: 45 pages, 17 figures. Revised resubmission to Computational Linguistic

Centering, Anaphora Resolution, and Discourse Structure

Centering was formulated as a model of the relationship between attentional state, the form of referring expressions, and the coherence of an utterance within a discourse segment (Grosz, Joshi and Weinstein, 1986; Grosz, Joshi and Weinstein, 1995). In this chapter, I argue that the restriction of centering to operating within a discourse segment should be abandoned in order to integrate centering with a model of global discourse structure. The within-segment restriction causes three problems. The first problem is that centers are often continued over discourse segment boundaries with pronominal referring expressions whose form is identical to those that occur within a discourse segment. The second problem is that recent work has shown that listeners perceive segment boundaries at various levels of granularity. If centering models a universal processing phenomenon, it is implausible that each listener is using a different centering algorithm.The third issue is that even for utterances within a discourse segment, there are strong contrasts between utterances whose adjacent utterance within a segment is hierarchically recent and those whose adjacent utterance within a segment is linearly recent. This chapter argues that these problems can be eliminated by replacing Grosz and Sidner's stack model of attentional state with an alternate model, the cache model. I show how the cache model is easily integrated with the centering algorithm, and provide several types of data from naturally occurring discourses that support the proposed integrated model. Future work should provide additional support for these claims with an examination of a larger corpus of naturally occurring discourses.Comment: 35 pages, uses elsart12, lingmacros, named, psfi

Discourse Anaphora

International audienceThis article is a characterisation of discourse anaphora. It highlights the cognitive as well as discursive dimensions of this context-bound referential procedure, which also involves (but is by no means limited to) purely co-textual factors. Discourse anaphora is conceived in terms of its intimate relation with deixis, and is distinguished from its close cousin, discourse deixis. Three essential components of discourse anaphora are detailed, namely the antecedent trigger, the "antecedent" (a salient discourse representation), and the anaphor as it functions within a given predicational context. Finally, these definitional aspects of the characterization are illustrated in concrete terms via a newspaper article. The text of this article is associated with its discourse structure, within which various topic chains are pinpointed and analysed. These are structured sequences of references to a single macro- or micro-topical discourse entity, references which are interconnected with the local as well as global discourse structure which is being developed as these acts of reference occur. The choice of referential markers (3rd person pronoun, definite or demonstrative NP, reduced definite or possessive NP, reduced repeated proper name, etc.) at any given link in a chain is shown to correlate both with the particular link in the chain which is being realised thereby, and with the local or global discourse structure within which that marker functions

Discourse Structure and Anaphora: An Empirical Study

ne of the main motivations for studying discourse structure is its effect on the search for the antecedents of anaphoric expressions. We tested the predictions in this regard of theories assuming that the structure of a discourse depends on its intentional structure, such as Grosz and Sidner?s theory. We used a corpus of tutorial dialogues independently annotated according to Relational Discourse Analysis (RDA), a theory of discourse structure merging ideas from Grosz and Sidner?s theory with proposals from Rhetorical Structure Theory (RST). Using as our metrics the accessibility of anaphoric antecedents and the reduction in ambiguity brought about by a particular theory, we found support for Moser and Moore?s proposal that among the units of discourse assumed by an RST-like theory, only those expressing an intentional ?core? (in the RDA sense) should be viewed as constraining the search for antecedents; units only expressing informational relations should not introduce separate focus spaces. We also found that the best compromise between accessibility and ambiguity (?perplexity?) reduction is a model in which the focus spaces associated with embedded cores and embedded contributors remain on the stack until the RDA-segment in which they occur is completed, and discuss the implications of this finding for a stack-based theory

Focusing for Pronoun Resolution in English Discourse: An Implementation

Anaphora resolution is one of the most active research areas in natural language processing. This study examines focusing as a tool for the resolution of pronouns which are a kind of anaphora. Focusing is a discourse phenomenon like anaphora. Candy Sidner formalized focusing in her 1979 MIT PhD thesis and devised several algorithms to resolve definite anaphora including pronouns. She presented her theory in a computational framework but did not generally implement the algorithms. Her algorithms related to focusing and pronoun resolution are implemented in this thesis. This implementation provides a better comprehension of the theory both from a conceptual and a computational point of view. The resulting program is tested on different discourse segments, and evaluation and analysis of the experiments are presented together with the statistical results.Comment: iii + 49 pages, compressed, uuencoded Postscript file; revised version of the first author's Bilkent M.S. thesis, written under the supervision of the second author; notify Akman via e-mail ([email protected]) or fax (+90-312-266-4126) if you are unable to obtain hardcopy, he'll work out somethin

Episodes as Memory Units in Discourse Representation: Anaphor Use in English and Mandarin

The present study investigates the relationship between cognitive constraints and discourse processing. In particular, it examines how the hierarchical structure of discourse is organized and presented, and what consequences that structure has for the linguistic coding employed during the dynamic time course of discourse processing. Special attention is directed to the distribution of full NPs and pronouns in discourse as a function of the location of episode boundaries. Results obtained from an experiment support the hypothesis that episode structure governs the alternative use of anaphora