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From a processing point of view, however, flexible categorial systems are problematic, since they introduce spurious ambiguity. In this paper, we present a flexible categorial grammar which makes extensive use of the product-operator, first introduced by Lambek (1958). The grammar has the property that for every reading of a sentence, a strictly left-branching derivation can be given. This leads to the definition of a subset of the grammar, for which the spurious ambiguity problem does not arise and efficient processing is possible. . | EFFICIENT PROCESSING OF FLEXIBLE CATEGORIAL GRAMMAR Gosse Bouma Research Institute for Knowledge Systems Postbus 463 6200 AL Maastricht The Netherlands e-mail earn exriksgb@hmarl5 ABSTRACT From a processing point of view however flexible categorial systems are problematic since they introduce spurious ambiguity. In this paper we present a flexible categorial grammar which makes extensive use of the product-operator first introduced by Lambek 1958 . The grammar has the property that for every reading of a sentence a strictly left-branching derivation can be given. This leads to the definition of a subset of the grammar for which the spurious ambiguity problem does not arise and efficient processing is possible. 1. Flexibility vs. Ambiguity Categorial Grammars owe much of their popularity to the fact that they allow for various degrees of flexibility with respect to constituent structure. From a processing point of view however flexible categorial systems are problematic since they introduce spurious ambiguity. The best known example of a flexible categorial grammar is a grammar containing the reduction rules application and composition and the category changing rule raising 1 I would like to thank Esther Kữnig Erik-Jan van der Linden Michael Moortgat Adriaan van Paas sen and the participants of the Edinburgh Categorial Grammar Weekend who made useful comments to earlier presentations of this material. All remaining errors and misconceptions are of course my own. 1 Throughout this paper we will be using the notation of Lambek 1958 in which A B and B A are a right-directional and a 1 application A B B A B B A A composition A B B C A C C B B A C A raising A B A B A B A B With this grammar many alternative constituent structures for a sentence can be generated even where this does not correspond to semantic ambiguities. From a linguistic point of view this has many advantages. Various kind of arguments for giving up traditional conceptions of constituent structure can .
