Building a Large-Scale Japanese Grammar

Abstract

Although large-scale grammars are prerequisite for parsing a great variety of sentences,it is difficult to build such grammars by hand.Yet,it is possible to derive a context-free grammar(CFG)automatically from an existing large-scale,syntactically annotated corpus.While seemingly a simple task,CFGs derived in such fashion have seldom been applied to existing systems.This is probably due to a great number of possible parse results(i.e.high ambiguity).In this paper,we analyze some causes of high ambiguity,and we propose a policy for building a large-scale Japanese CFG for syntactic parsing,capable of decreasing ambiguity.We also provide an experimental evaluation of the obtained CFG showing reduction in the number of parse results (reduced ambiguity)created by the CFG and the improved parsing accuracy.

Preference Dependency Grammar and its Packed Shared Data Structure “Dependency Forest”

“…Spurious ambiguity (Noro, Okazaki, Tokunaga, and Tanaka 2002) (Noro, Hashimoto, Tokunaga, and Tanaka 2005). Although it is not CFG, CCG has many spurious ambiguities because of the flexibility of rule application.…”