tailieunhanh - Báo cáo khoa học: "Functional Unification Grammar Revisited"

In this paper, we show that one benefit of FUG, the ability to state global conslralnts on choice separately from syntactic rules, is difficultin generation systems based on augmented context free grammars (., Def'mite Clause Cn'anmm~). They require that such constraints be expressed locally as part of syntactic rules and therefore,duplicated in the grammar. Finally, we discuss a reimplementation of l U g that achieves the similar levels of efficiency as Rubinoff's adaptation of M U M B L E , a detcrministc language generator. . | Functional Unification Grammar Revisited Kathleen R. McKeown and Cecile L. Paris Department of Computer Science 450 Computer Science Columbia University ______New York . 10027 MCKEOWN@ CECILE@ Abstract In this paper we show that one benefit of FUG the ability to state global constraints on choice separately from syntactic rules is difficult in generation systems based on augmented context flee grammars . Definite Clause Grammars . They require that such constraints be expressed locally as part of syntactic rules and therefore duplicated in the grammar. Finally we discuss a reimplementation of FUG that achieves the similar levels of efficiency as Rubinoffs adaptation of MUMBLE a deterministic language generator. 1 Introduction ___ Inefficiency of functional unification grammar FUG 5 has prompted some effort to show that the same benefits offered by FUG can be achieved in other formalisms more efficiently 3 14 15 16 . In this paper we show that one benefit of FUG the ability to concisely state global constraints on choice in generation is difficult in other formalisms in which we have written generation systems. In particular we show that a global constraint can be stated separately from syntactic rules in FUG while in generation systems based on augmented context free grammars . Definite Clause Grammars DCG 13 such constraints must be expressed locally as part of syntactic rules and therefore duplicated in the grammar. Finally we discuss a reimplementation of FUG in TAILOR 11 1ỊÍ that achieves the similar levels of efficiency as Rubmoff s adaptation 16 of MUMBLE 7 a deterministic language generator. Statement of Constraints Language generation can be viewed primarily as a problem of choice requiring decisions about which syntactic structures best express intent As a result much research in language generation has focused on identifying constraints on choice and it is important to be able to represent these constraints .