# Pregroup Grammars and Context-free Grammars

@inproceedings{Buszkowski2007PregroupGA, title={Pregroup Grammars and Context-free Grammars}, author={W. Buszkowski and K. Moroz}, year={2007} }

Pregroup grammars were introduced by Lambek [20] as a new formalism of type-logical grammars. They are weakly equivalent to context-free grammars [8]. The proof in one direction uses the fact that context-free languages are closed under homomorphism and inverse homomorphism. Here we present a direct construction of a context-free grammar and a push-down automaton, equivalent to a given pregroup grammar. The size of the resulting contextfree grammar (push-down automaton) is polynomial in the… Expand

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#### 20 Citations

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Pregroups and pregroup grammars were introduced by Lambek in 1999 [14] as an algebraic tool for the syntactic analysis of natural languages. The main focus in that paper was on certain extended… Expand

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The Letter Promotion Problem for pregroups is solvable in polynomial time, if the size of p(n) is counted as |n|+1, and the problem is reduced to a graph-theoretic problem, which is subsequently reduced to the emptiness problem for context-free languages. Expand

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