HPSG-style underspecified Japanese grammar with wide coverage

Abstract

This paper describes a wide-coverage Japanese grammar based on HPSG. The aim of this work is to see the coverage and accuracy attainable using an underspecified grammar. Underspecification, allowed in a typed feature structure formalism, enables us to write down a wide-coverage grammar concisely. The grammar we have implemented consists of only 6 ID schemata, 68 lexical entries (assigned to functional words), and 63 lexical entry templates (assigned to parts of speech (POSs)). Furthermore. word-specific constraints such as subcategorization of verbs are not fixed in the grammar. However, this grammar can generate parse trees for 87% of the 10000 sentences in the Japanese EDR corpus. The dependency accuracy is 78% when a parser uses the heuristic that every bunsetsu is attached to the nearest possible one.