Affiliation:
1. Leipzig University Faculty of Mathematics and Computer Science. schiffer@informatik.uni-leipzig.de
2. Linköping University Department of Computer and Information Science. marco.kuhlmann@liu.se
3. University of Padua Department of Information Engineering. satta@dei.unipd.it
Abstract
Abstract
Unlike other mildly context-sensitive formalisms, Combinatory Categorial Grammar (CCG) cannot be parsed in polynomial time when the size of the grammar is taken into account. Refining this result, we show that the parsing complexity of CCG is exponential only in the maximum degree of composition. When that degree is fixed, parsing can be carried out in polynomial time. Our finding is interesting from a linguistic perspective because a bounded degree of composition has been suggested as a universal constraint on natural language grammar. Moreover, ours is the first complexity result for a version of CCG that includes substitution rules, which are used in practical grammars but have been ignored in theoretical work.
Subject
Artificial Intelligence,Computer Science Applications,Linguistics and Language,Language and Linguistics
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