Toward the construction of linguistically-valid CCG treebank

Abstract

Constructing linguistically valid CCG treebanks is necessary since CCG parsing often uses CCG treebanks as training and evaluation data. However, it is known that the current Japanese CCG treebank, CCGbank, incorrectly analyzes Japanese syntactic structures, including passive and causative constructions. The ABCTreebank, a treebank for ABC grammar, has made many improvements, such as argument structures. However, it does not describe the detailed syntactic features of Japanese CCG. Meanwhile, the output of the Japanese CCG parser, lightblue, successfully provides the syntactic structures with detailed syntactic features but faces the challenge of capturing the argument structures correctly. In this study, we propose a method to generate a Japanese treebank with more linguistically valid and detailed information by combining the advantages of the ABCTreebank with lightblue. We develop an algorithm to filter lightblue's lexical items using ABCTreebank and construct a linguistically valid CCG treebank by transforming the output of lightblue.