Filtering Left Dislocation Chains in Parsing Categorial Grammar

Abstract

This paper reports on a way to reduce the complexity of the process of left dislocation (re)construction for categorial grammar in the case of lexically assigned gaps, as an additional restriction on the complexity arising from lexical polymorphism in general. Specifying extraction sites lexically has the advantage that the combinatory explosion can be contained in the preparsing track by a specialized constraint on the expansion of sequences of categories. This constraint is called the Left Dislocation Chain Filter and is implemented by a Finite State Transducer. It is shown that the Filter can reduce the number of full string assignments under consideration prior to parsing with an average of one half to one order of magnitude, depending on the nature of the sentence. 1 Parsing Left Dislocation Left dislocation is a very common, almost universal phenomenon in natural languages. It establishes the relation between an element at the left periphery of a clause and a particular, lexical..