tailieunhanh - Báo cáo khoa học: "FOR A N EFFICIENT CONTEXT-FREE PARSER AUGMENTED PHRASE-STRUCTURE GRAMMARS"

In this paper we present an efficient context-free (CF) bottom-up, non deterministic parser. It is an extension of the ICA (Immediate Constituent Analysis) parser proposed by Grishman (1976), and its major improvements are described. It has been designed to run Augmented Phrase-Structure Grammars (APSG) and performs semantic interpretation in parallel with syntactic analysis. It has been implemented in Franz Lisp and runs on VAX 11/780 and, recently, also on a SUN workstation, as the main component of a transportable Natural Language Interface (SAIL = Sistema per I'Analisi e I'lnterpretazione del Linguaggio). . | AN EFFICIENT CONTEXT-FREE PARSER FOR AUGMENTED PHRASE-STRUCTURE GRAMMARS Massimo Marino Antonella spiezio Giacomo Ferrari Irina Prodanof Linguistics Department University of Pisa Via s. Maria 36 1-56100 Pisa - Italy Computational Linguistics Institute - Cnr Via Della Faggiola32 1-56100 Pisa - Italy ABSTRACT In this paper we present an efficient context-free CF bottom-up non deterministic parser. It is an extension of the ICA Immediate Constituent Analysis parser proposed by Grishman 1976 and its major improvements are described. It has been designed to run Augmented Phrase-Structure Grammars APSG and performs semantic interpretation in parallel with syntactic analysis. It has been implemented in Franz Lisp and runs on VAX 11 780 and recently also on a SUN workstation as the main component of a transportable Natural Language Interface SAIL Sistema per I Analisi e I lnterpretazione del Linguaggio . Subsets of grammars of Italian written in different formalisms and for different applications have been experimented with SAIL. In particular a toy application has been developed in which SAIL has been used as interface to build a knowledge base in MRS Genesereth et al. 1980 Genesereth 1981 about ski paths in a ski environment and to ask for advice about the best touristic path under specific weather and physical conditions. 1. INTRODUCTION Many parsers for natural language have been developed in the past which run different types of grammars. Among them the most successful are the CF grammars the augmented phrase-structure grammars APSGs and the semantic grammars. All of them have different characteristics and different advantages. In particular APSGs offer a natural tool for the treatment of certain natural language phenomena such as subjectverb agreement. Semantic grammars are prone to a compositional algorithm for semantic interpretation. The aim of our work is to implement a parser which associates the full extension of an APSG to compositionality of semantics. The .