A Game-Theoretic Model of Referential Coherence and Its Statistical Verification Based on Large Japanese and English Corpora

概要

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Referential coherence represents smoothness of discourse resulting from topic continuity and pronominalization. By what principle do we select coherent expressions and interpretations? Centering theory, the standard theory of referential coherence, has not modeled the mechanism for selection of coherent expressions and interpretations. Our goals are as follows: (1) We aim to verify the hypothesis that models the principle of selecting expressions and interpretations on the basis of game theory (Hasida et al. 1995; Shiramatsu et al. 2005), using corpora of multiple languages.(2) We aim to investigate whether we can use expected utility as selection criterion, and to develop the mechanism of selecting expressions and interpretations for discourse processing systems in various languages.<BR>For these purposes, we improved the meaning-game-based centering model (MGCM).Our improvement, the statistical design of the language-dependent parameters, enabled to acquire the parameters from a corpus of the target language. It also enabled verification of MGCM using corpora of various languages. We verified MGCM using Japanese and English corpora. We found out statistical evidences which supported the hypothesis that referential coherence was caused by selection with higher expected utility. This result indicates language universality of MGCM and the hypothesis.
言語処理学会の論文