Abstract
It is necessary to clarify referents of pronouns in machine translation and conversational processing. We present a method of estimating referents of demonstrative pronouns, personal pronouns, and zero pronouns in Japanese sentences using examples, surface expressions, topics and focuses. In conventional work, semantic markers have been used for semantic constraints. On the other hand, we use examples for semantic constraints and show that examples are as useful as semantic markers through control experiments. We also propose many new methods for estimating referents of pronouns. For example, we use examples of the form “A of B” for estimating referents of demonstrative adjectives. The framework of estimating referents is as follows. We make the rules from the informations that are necessary for estimating referents of pronouns.By these rules, we list possible referents of a pronoun and give them points.We estimate that the possible referent with the highest score is the referent.This framework has the advantage of writing rules flexibly. When we experimented in this framework, we obtained a precision rate of 87% in the estimation of referent of demonstrative pronouns, personal pronouns, and zero pronouns on training sentences, and obtained a precision rate of 78% on held-out test sentences.
