tailieunhanh - Báo cáo khoa học: "A Model-Theoretic Framework for Theories of Syntax"

A natural next step in the evolution of constraint-based grammar formalisms from rewriting formalisms is to abstract fully away from the details of the grammar mechanism--to express syntactic theories purely in terms of the properties of the class of structures they license. By focusing on the structural properties of languages rather than on mechanisms for generating or checking structures that exhibit those properties, this model-theoretic approach can offer simpler and significantly clearer expression of theories and can potentially provide a uniform formalization, allowing disparate theories to be compared on the basis of those properties. . | A Model-Theoretic Framework for Theories of Syntax James Rogers Institute for Research in Cognitive Science University of Pennsylvania Suite 400C 3401 Walnut Street Philadelphia PA 19104 Abstract A natural next step in the evolution of constraint-based grammar formalisms from rewriting formalisms is to abstract fully away from the details of the grammar mechanism to express syntactic theories purely in terms of the properties of the class of structures they license. By focusing on the structural properties of languages rather than on mechanisms for generating or checking structures that exhibit those properties this model-theoretic approach can offer simpler and significantly clearer expression of theories and can potentially provide a uniform formalization allowing disparate theories to be compared on the basis of those properties. We discuss L2K p a monadic second-order logical framework for such an approach to syntax that has the distinctive virtue of being superficially expressive supporting direct statement of most linguistically significant syntactic properties but having well-defined strong generative capacity languages are definable in L2K p iff they are strongly context-free. We draw examples from the realms of GPSG and GB. 1 Introduction Generative grammar and formal language theory share a common origin in a procedural notion of grammars the grammar formalism provides a general mechanism for recognizing or generating languages while the grammar itself specializes that mechanism for a specific language. At least initially there was hope that this relationship would be informative for linguistics that by characterizing the natural languages in terms of language-theoretic complexity one would gain insight into the structural regularities of those languages. Moreover the fact that language-theoretic complexity classes have dual automata-theoretic characterizations offered the prospect that such results might provide abstract models