A METHOD OF CASE STRUCTURE-ANALYSIS FOR JAPANESE SENTENCES BASED ON EXAMPLES IN CASE FRAME DICTIONARY

A case structure expression is one of the most important forms to repr esent the meaning of the sentence. Case structure analysis is usually performed by consulting case frame information in a verb dictionary. H owever, this analysis is very difficult because of several problems, s uch as word sense ambiguity and structural ambiguity. A conventional m ethod for solving these problems is to use the method of selectional r estriction, but this method has a drawback in the semantic marker (SM) method - the trade-off between descriptive power and construction cos t. In this paper, we propose a method of case structure analysis based on examples in case frame dictionary This method uses the case frame dictionary which has some typical example sentences for each case fram e, and it selects a proper case frame for an input sentence by matchin g the input sentence with the examples in the case frame dictionary. T he best matching score, which is utilized for selecting a proper case frame for a predicate, can be considered as the score for the case str ucture of the predicate. Therefore, when there are two or more reading s for a sentence because of structural ambiguity, the best reading of a sentence can be selected by evaluating the sum of the scores for the case structures of all predicates in a sentence. We report on experim ents which shows that this method is superior to the conventional, coa rse-grained SM method, and also describe the superiority of the exampl e-based method over the SM method.