Anaphora Resolution of Japanese Zero Pronouns with Deictic Reference

This paper proposes a method to resolve the reference of deictic Japanese zero pronouns which can be implemented in a practical machine translation system. This method focuses on semantic and pragmatic constraints such as semantic constraints on cases, modal expressions, verbal semantic attributes and conjunctions to determine the deictic refernce of Japanese zero pronouns. This method is highly effective because the volume of knowledge that must be prepared before-hand is not very large and its precision of resolution is good. This method was implemented in the Japanese-to-English machine translation system, ALT-J/E. According to a window test for 175 zero pronouns with deictic referent in a sentence set for the evaluation of Japanese-to-English machine translation systems, all of zero pronouns could be resolved consistently and correctly.