The University of Sussex

Theoretical and computational interpretations of Generalised Phrase Structure Grammar

Roger Evans

This thesis explores the relationship between Generalised Phrase Structure Grammar (GPSG) as a formal theory of natural language syntax and the applications of it in the computational domain. Traditionally, the appeal of GPSG to the computational linguist has arisen largely from its interpretation as encoding high level descriptions of `underlying' context-free grammars. This has had two main effects: firstly little attention has been paid to the computational properties of the high level GPSG grammars themselves - computational exploitation of the various syntactic generalisations captured in GPSG at the highest levels is almost nonexistent - and secondly insight gained from computational work can generally only be expressed in terms of the lower level underlying representation, and so is inappropriate for application to the theory itself. Hence interdisciplinary communication is only one-way (from theoretical to computational linguistics) and even that is not exploited to the fullest extent.

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