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Approximating Context-Free Grammars with a Finite-State Calculus

Edmund Grimley-Evans
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Abstract

Although adequate models of human language for syntactic analysis and semantic interpretation are of at least context-free complexity, for applications such as speech processing in which speed is important finite-state models are often preferred. These requirements may be reconciled by using the more complex grammar to automatically derive a finite-state approximation which can then be used as a filter to guide speech recognition or to reject many hypotheses at an early stage of processing. A method is presented here for calculating such finite-state approximations from context-free grammars. It is essentially different from the algorithm introduced by Pereira and Wright (1991; 1996), is faster in some cases, and has the advantage of being open-ended and adaptable.

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Edmund Grimley-Evans. 1997-11-11. Approximating Context-Free Grammars with a Finite-State Calculus. https://arxiv.org/abs/cmp-lg/9711002

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