tailieunhanh - Báo cáo khoa học: "ANALYSIS OF OONOUNCTIONS IN PAKSER"

The aim of the present paper is to show how a rule-based parser for the Italian language has been extended to analyze sentences involving conjunctions. The most noticeable fact is the ease with ~4nich the required modifications fit in the previous parser structure. In particular, the rules written for analyzing simple sentences (without conjunctions) needed only small changes. On the contrary, more substantial changes were made to the e~oeption-handling rules (called "natural changes") that are used to restructure the tree in case of failure of a syntactic hypothesis. . | ANALYSIS OF CONJUNCTIONS IN A RULE-BASED PARSER Leonardo Lesno and Pietro Tbrasso Dipartimento di Informatica - Universita di Torino Via Valperga Caluso 37 - 10125 Torino ITALY ABSTRACT The aim of the present paper is to show how a rule-based parser for the Italian language has been extended to analyze sentences involving conjunctions. The most noticeable fact is the ease with which the required modifications fit in the previous parser structure. In particular the rules written for analyzing simple sentences without conjunctions needed only snail changes. On the contrary more substantial changes were made to the exception-handling rules called natural changes that are used to restructure the tree in case of failure of a syntactic hypothesis. The parser described in the present work constitutes the syntactic component of the FIDO system a Flexible Interface for Database Operations an interface allowing an end-user to access a relational database in natural language Italian . INTRODUCTION It is not our intention to present here a comprehensive overview of the previous work on coordination but just to describe a couple of recent studies on this topic and to specify the main differences between them and our approach. It must be noticed however that both systems that will be discussed use a logic granrnar as their basic framework so that we will try to make the comparison picking out the basic principles for the manipulation of conjunctions and disregarding the more fundamental differences concerning the global system design. It is also worth pointing out that although the present section is admittedly incomplete most of the systems for the automatic analysis of natural language do not describe the methods adopted for the interpretation of sentences containing conjunctions in great detail. Therefore it is reasonable to assume that in many of these systems the conjunctions are handled only by means of specific neuristic mechanisms. A noticeable exception is the SYSCONJ .