A PROLOG Implementation of Lexical Functional Grammar

Abstract

L exical functional grammar (LPG) is an attempt to solve problems that arise in transformational grammar and ATN-formalisms (Bresnan, 19 82) . Another powerful formalism for describing natural languages follows from a method for expressing grammars in logic, due to Colmerauer (1978) and Kowalski (1974) called definite clause grammars (DCG) (Warren, Pereira, 1 980) . Both formalisms are a naturalexte nsion o f context free grammars (CFG) . The aim of this paper is to show - how LPG ca n be translated into DCG that the procedural semantics of PROLOG provides an eff icient tool for LFG-implementations in that it allows the construction of function structures (f-structures) directly during the parsing process . I.e . it is not necessary to have a separate component which first derives a set of functional equations from the parse tree, and second ly generates a f-structure by solving these eq uations.