Abstract
This paper describes a Japanese computational grammar on the basis of Lexical Functional Grammar toward a practical parser with deep analysis for Japanese sentences. The Japanese grammar is characterized by (1) broad coverage even for colloquial or ungrammatical sentences, (2) linguistic preciseness to output f-structures with rich information, and (3) consistency with grammars for other languages. It is a difficult task to develop a computational grammar systematically or in a procedural way, and our grammar writing also depends on our own experience. However, a gradual analysis method using Optimality Theory marks can prevent exceptional rules from causing unexpected analysis results. and a fragment analysis method makes it DOSsible to deal with colloquial or ungrammatical sentences. These two methods give a clear perspective on writing the grammar. We conducted experiments to evaluate our parser with grammatical text (manual text) and colloquial and ungrammatical text (“Voice of Customer” text). The coverage was over 95 %, and the predicate dependency accuracy was 84%.
