Japanese Categorial Grammar Based on Term and Sentence

JAPANESE CATEGORIAL GRAMMAR BASED ON TERM AND SENTENCE Hisashi Komatsu School of Information Sciences, Hiroshima City University, 3-4-1 Ozuka-higashi, Asa-ininami-ku, Hiroshima 731-3194, Japan e-mail: komatsuqcs.hiroshima-cu.ac.jp ABSTRACT In this paper, I propose a japanese categorial grammar JCG which gives a foundation of semantic parsing of Japanese. JCG is not an orthodox categorial grammar with functional application, composition etc., but a hybrid system with HPSG based on term and sentence which correspond to the nominal head and verbal head in HPSG respectively. Construction rules of JCG are designed so as to be used as parsing rules of Japanese, but at the same time, they give the semantic correspondence of the japanese expressions via the homomorphism between syntax and semantics. The semantic output as such is a higher-order logical expression, but it's reduced to a Horn clause expression in its final form that constitutes a logic database on which a logical inference is executed. 1 Introduction The phrase structure grammar which stems from the structural linguistics and was adopted by the generative transformational grammar has been the main grammatical theory of parsing of English. It is further applied - often without critical consideration - to other languages, also to Japanese. It certainly provides an effective tool for the syntactic parsing, but when it comes to the semantic parsing of Japanese, it seems preferable to adopt the categorial grammatical approach which reflects the semantics of Japanese in a direct form, all the more because the word order of Japanese is based on the inverse Polish notation, in contrast to English syntax based on the syntagmatic distribution of formatives. There has also been a categorial grammatical approach to the parsing which originates in the exploring work of Bar-Hillel(1953) followed by Urzkoreit(1986), Moortgat(1988), Wood(1993), Carpenter(1997) to mention a few. But the strict categorial combinatorics contradicts the free word order of Japanese and the frequent elimination of sentence elements, to make it difficult to apply the original categorial grammatical method to Japanese. So, as to the essential part of Japanese, I abandon the simple categorial grammatical technique such as application, composition, division etc., and introduce the HPSG-like compositional principle based on term and sentence.1 One of the basic ideas for this stems from Sakai(1979) who advocates the view that japanese verbs and adjectives are all sentences as such, and missing arguments are implicitely complemented by the context. According to this view, the following sentence (1) Taro-ga� ringo-wo� tabe-ta (Taro-NomCM apple-AccCM eat-Past) (Taro ate an apple.) (NomCM: nominative case marker, AccCM: accusative case marker, Past: past tense marker) is analyzed as follows: (2) [[Taro-ga] t Rringo-wol t [tabe-ta]8ls}, (t: category of terms, s: category of sentences) -153- I.e., the term `ringo-wo is applied to the sentence `tabe-ta' to form the sentence ‘ringo-wo tabe-ta', further the term `Taro-ga' is applied to the sentence `ringo-wo tabe-ta' to form the sentence (1). Here, the expressions (3) i) tabe-ta ii) ringo-wo tabe-ta iii) Taro-ga ringo-wo tabe-ta are all grammatical sentences. And the sentence (the transitive verb in its usual terminology) `tabe-ta' functions …

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