tailieunhanh - Báo cáo khoa học: " LOCALIZATION STRATEGIES BLEM IN NATURAL-LANGUAGE FRONT ENDS"

Problem localization Is the identification of the most slgnlflcant failures i n the AND-OR tree resulting from an unsuocass/ul attempt to achieve a goal, for instance, In planning, b a c k w a r d - c h n i n i n g inference, or top-down parnin~ We examine beurlstics and strategies for problem localization in the context of using a planner to check for pragmatic failures in natural language input to computer systems, such as a cooperative natural language interface to Unix . | BBQBLEM LOCALIZATION STRATEGIES EQB PRAGMATICS PROCESSING IN NATURAL-LANGPAGE FRONT ENDS Lance A. Ramshaw Ralph M. Weischedel Department of Computer and Information Sciences University of Delaware Newark Delaware 19716 USA ABSTRACT Problem localization is the identification of the most significant failures in the AND-OR tree resulting from an unsuccessful attempt to achieve a goal for instance in planning backward-chaining inference or top-down parsing. We examine heuristics and strategies for problem localization in the context of using a planner to check for pragmatic failures in natural language input to computer systems such as a cooperative natural language interface to Unix . Our heuristics call for selecting the most hopeful branch at ORs but the most problematic one at ANDs. Surprise scores and special-purpose rules are the main strategies suggested to determine this. I PRAGMATIC OVERSHOOT AND PROBLEM LOCALIZATION Even if the syntactic and semantic content of a request is correct so that a natural language front end can derive a coherent representation of Its meaning its pragmatic content or the structure of the underlying system may make any direct response to the request impossible or misleading. According to Sondhelmer and Weischedel Sondhelmer 1980 an input exhibits pragmatic overshoot if the representation of Its meaning Is beyond the capabilities of the underlying system. Kaplan 1979 Mays 1980a and Carberry 1984 have each worked on strategies for dealing with particular classes of such pragmatic failures. This paper addresses the problem of Identifying the most significant reason that a plan to achieve a user goal cannot be carried out. The approach to pragmatic failure taken In this paper is to use a planner to verify the presunptions In a request. The presumptions behind a request become the subgoals of a plan to fulfill the request. Using Mays 1980a example the query Which faculty members take courses Is here handled as an instance of an .