tailieunhanh - Báo cáo khoa học: "USING %-CALCULUS TO REPRESENT IN LOGIC GRAMMARS"

This paper descrlbes how meanings are represented in a semantic grammar for a fragment of English in the logic programming language Prolog. The conventions of Definite Clause Grammars are used. Previous work on DCGs with a semantic component has used essentially first-order formulas for representing meanings. The system described here uses formulas of the typed ~-calculus. The first section discusses general issues concerning the use of first-order logic or the h-calculus to represent meanings, The second section describes how h-calculus meaning representations can be constructed and manipulated directly in Prolog. This 'programmed' representation motivates a suggestion, discussed in. | USING X-CALCULUS TO REPRESENT MEANINGS IN LOGIC GRAMMARS David Scott Warren Computer Science Department SUNY at Stony Brook Stony Brook NY 11794 ABSTRACT This paper describes how meanings are represented in a semantic grammar for a fragment of English in the logic programming language Prolog. The conventions of Definite Clause Grammars are used. Previous work on DCGs with a semantic component has used essentially first-order formulas for representing meanings. The system described here uses formulas of the typed X-calculus. The first section discusses general issues concerning the use of first-order logic or the x-calculus to represent meanings. The second section describes how X-calculus meaning representations can be constructed and manipulated directly In Prolog. This programmed representation motivates a suggestion discussed in the third section for an extension to Prolog so that the language Itself would Include a mechanism for handling the x-formulas directly. I X-CALCULUS AND FOL AS MEANING REPRESENTATION LANGUAGES The initial phase of most computer programs for processing natural language is a translation system. This phase takes the English text input and transforms it into structures In some Internal meaning-representation language. Most of these systems fall into one of two groups those that use a variant of first-order logic FOL as their representation language and those that use the typed x-calculus LC for their representation language. Systems based on semantic nets or conceptual dependency structures would generally be calssified as using variants of FOL but see Jones and Warren 1982 for an approach that views them as LC-based. The system considered here are several highly formalized grammar systems that concentrate on the translation of sentences of logical form. The first-order logic systems are exemplified by those systems that have developed around or gravitated to logic programming and the Prolog language in particular. These include the systems