Extraction of Preference of Dependency between Japanese Subordinate Clauses from Corpus and its Evaluation

Abstract

Dependeny analysis of Japanese subordinate clauses is one of the most difficult phases in the syntactic analysis of Japanese long sentences. This paper proposes a corpus-based method of learning preference rules of deciding dependency relation of Japanese subordinate clauses. We utilize morphological cues included in the subordinate clauses and statistically estimate the co-relation of those cues and dependency relation of Japanese subordinate clauses. Especially, we exploit scope embedding preference of subordinate clauses as a useful information source for disambiguating dependencies between subordinate clauses. In the experimental evalution on EDR Japanese parsed corpus, we discover that there exist several morphological cues that are quite effective in deciding dependency relation of Japanese subordinate clauses. We also show that the estimated dependencies of subordinate clauses successfully increase the accuracy of an existing statistical dependency analyzer.