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We propose a generalization of Categorial Grammar in which lexical categories are defined by means of recursive constraints. In particular, the introduction of relational constraints allows one to capture the effects of (recursive) lexical rules in a computationally attractive manner. We illustrate the linguistic merits of the new approach by showing how it accounts for the syntax of Dutch cross-serial dependencies and the position and scope of adjuncts in such constructions. Delayed evaluation is used to process grammars containing recursive constraints. . | Constraint-Based Categorial Grammar Gosse Bouma and Gertjan van Noord Alfa-informatica and Behavorial and Cognitive Neurosciences Rijksuniversiteit Groningen gosse vannoord @let.rug.nl Abstract We propose a generalization of Categorial Grammar in which lexical categories are defined by means of recursive constraints. In particular the introduction of relational constraints allows one to capture the effects of recursive lexical rules in a computationally attractive manner. We illustrate the linguistic merits of the new approach by showing how it accounts for the syntax of Dutch cross-serial dependencies and the position and scope of adjuncts in such constructions. Delayed evaluation is used to process grammars containing recursive constraints. 1 Introduction Combinations of Categorial Grammar cg and unification naturally lead to the introduction of polymorphic categories. Thus Karttunen 1989 categorizes Np s as x x where X is a verbal category Zeevat et al. 1987 assign the category x np x to NP s and Emms 1993 extends the Lambek-calculus with polymorphic categories to account for coordination quantifier scope and extraction. The role of polymorphism has been restricted however by the fact that in previous work categories were defined as feature structures using the simple nonrecursive constraints familiar from feature description languages such as PATR. Relational constraints can be used to define a range of polymorphic categories that are beyond the expressive capabilities of previous approaches. In particular the introduction of relational constraints captures the effects of recursive lexical rules in a computationally attractive manner. The addition of such rules makes it feasible to consider truly lexical-ist grammars in which a powerful lexical component is accompanied by a highly restricted syntactic component consisting of application only. 2 Recursive Constraints In CG many grammatical concepts can only be defined recursively. Dowty 1982 defines grammatical
