Effectiveness of Indirect Dependency for Automatic Synonym Acquisition

Since synonyms are important lexical knowledge, various methods have been proposed for automatic synonym acquisition. Whereas most of the methods are based on the distributional hypothesis and utilize contextual clues, little attention has been paid to what kind of contextual information is useful for the purpose. As one of the ways to augment contextual information, we propose the use of indirect dependency, i.e. relation between two words related via two contiguous dependency relations. The evaluation has shown that the performance improvement over normal direct dependency is dramatic, yielding comparable results with surrounding words as context, even with smaller co-occurrence data.