Dependency-structure Annotation to Corpus of Spontaneous Japanese

In Japanese, syntactic structure of a sentence is generally represented by the relationship between phrasal units, or bunsetsus in Japanese, based on a dependency grammar. In the same way, the syntactic structure of a sentence in a large, spontaneous, Japanese-speech corpus, the Corpus of Spontaneous Japanese (CSJ), is represented by dependency relationships between bunsetsus. This paper describes the criteria and definitions of dependency relationships between bunsetsus in the CSJ. The dependency structure of the CSJ is investigated, and the difference in the dependency structures of written text and spontaneous speech is discussed in terms of the dependency accuracies obtained by using a corpus-based model. It is shown that the accuracy of automatic dependency-structure analysis can be improved if characteristic phenomena of spontaneous speech — such as self-corrections, basic utterance units in spontaneous speech, and bunsetsus that have no modifiee — are detected and used for dependency-structure analysis.