Automatic Detection of Antecedents of Japanese Zero Pronouns Using a Japanese-English Bilingual Corpus

In this paper we present a method of detecting zero pronouns in Japanese clauses and identifying their antecedents using aligned sentence pairs from a Japanese-English bilingual corpus and open resource tools. We use syntactic and semantic structures and the alignment of words and phrases in the sentence pairs to automatically detect zero pronouns and determine their antecedents using English translations. We build rules to link antecedents with zero pronouns and create filters to remove problematic sentence pairs. Experimental results confirm the effectiveness of our method. The proposed method allows the construction of an annotated corpus of zero pronoun sentences in which the antecedents of the missing pronouns are flagged. This would be very useful for machine translation (MT), because zero pronoun detection is a vital problem when translating languages which allow zero pronouns.