Automatic Extraction of Rules for AnaphoraResolution of Japanese Zero Pronouns in Japanese–English Machine Translation from Aligned Sentence Pairs

• Authors: Hiromi Nakaiwa
• Venue: Machine Translation
• Year: 1999

This paper proposes a method to extract rules for the anaphora resolution of Japanese zero pronouns in Japanese–English MT from aligned sentence pairs. After aligned sentence pairs unsuitable for rule extraction because of analysis errors or free translations are automatically rejected, zero pronouns in the Japanese sentences and the English translation equivalents of their antecedents are extracted from the remaining Japanese and English aligned sentence pairs using ten hand-developed alignment rules. This method identifies all Japanese zero pronouns whose translation equivalents are not explicitly expressed in an English sentence, this method identifies these as unalignable. Then, resolution rules for the remaining zero pronouns are automatically extracted using the aligned pairs, equivalent word/phrase pairs extracted from the aligned sentence pairs, and the syntactic and semantic structures of the Japanese sentences. This method was implemented in a Japanese–English MT system, ALT-J/E. 98.4% of all pairs were automatically aligned correctly in a window test, and 94.0% in a blind test. Furthermore, extracted rules for zero pronouns with deictic references created automatically from sentence pairs correctly resolved 99.0% of the zero pronouns in a window test and 85.0% of the zero pronouns in a blind test.