Japanese Case Structure Analysis by Unsupervised Construction of a Case Frame Dictionary

In Japanese, case structure analysis is very important to handle several troublesome characteristics of Japanese such as scrambling, omission of case components, and disappearance of case markers. However, for lack of a widecoverage case frame dictionary, it has been difficult to perform case structure analysis accurately. Although several methods to construct a case frame dictionary from analyzed corpora have been proposed, they cannot avoid data sparseness problem. This paper proposes an unsupervised method of constructing a case frame dictionary from an enormous raw corpus by using a robust and accurate parser. It also provides a case structure analysis method based on the constructed dictionary.