tailieunhanh - Báo cáo khoa học: "LAMBEK THEOREM PROVING AND FEATURE UNIFICATION"

it follows as a theorem from a set of axioms and inference rules. Especially by the work of Van Benthem (1986) and Moortgat (1988) this view, which we will name with Moortgat (1987a) Lambek Theorem Proving (LTP; Lambek, 1958), has become popular among a number of linguists. The descriptive power of LTP can be extended if unification (Shieber, 1986) is added. Several theories have been developed that combine categorial formalisms and unification based formalisms. Within Unification Categorial Grammar (UCG, Calder et al., 1988, Zeevat et al., 1986) unification "is the only operation over grammatical objects" (Calder et al. 1988,. | LAMBEK THEOREM PROVING AND FEATURE UNIFICATION Erik-Jan van der Linden Institute for Language Technology and Artificial Intelligence Tilburg University PO Box 90153 5000 LE Tilburg The Netherlands 1 ABSTRACT Feature Unification can be integrated with Lam-bek Theorem Proving in a simple and straightforward way. Two principles determine all distribution of features in LTP. It is not necessary to stipulate other principles or include category-valued features where other theories do. The structure of categories is discussed with respect to the notion of category structure of Gazdar et al. 1988 . 2 INTRODUCTION A tendency in current linguistic theory is to shift the explanatory burden from the syntactic component to the lexicon. Within Categorial Grammar CG this so-called lexicalist principle is implemented in a radical fashion syntactic information is projected entirely from category structure assigned to lexical items Moortgat 1988 . A small set of rules like 1 constitutes the grammar. The rules reduce sequences of categories to one category. 1 X a X Y b Y b a CG implements the Compositionality Principle by stipulating a correspondence between syntactic operations and semantic operations Van Benthem 1986 . An approach to the analysis of natural language in CG is to view the categorial reduction system the set of reduction rules as a calculus where parsing of a syntagm is an attempt to prove that Port of the research described in this paper was carried out within the Categorial Parser Project at ITI-TNO. I wish to thank the people whom I had the pleasure to cooperate with within this project Brigit van Berkel Michael Moortgat and Adriaan van Paassen. Gosse Bourns Harry Bunt Bart Geurts Elias Thijsse Ton van der Wouden and three anonymous ACL reviewers made stimulating comments on earlier versions of this paper. Michael Moortgat generously supplied a copy of the interpreter described in his 1988 dissertation it follows as a theorem from a set of axioms and inference .