tailieunhanh - Báo cáo khoa học: "What's in a Semantic Network?"

Ever since Woods's "What's in a Link" paper, there has been a growing concern for formalization in the study of knowledge representation. Several arguments have been made that frame representation languages and semantic-network languages are syntactic variants of the ftrst-order predicate calculus (FOPC). The typical argument proceeds by showing how any given frame or network representation can be mapped to a logically isomorphic FOPC representation. For the past two years we have been studying the formalization of knowledge retrievers as well as the representation languages that they operate on. . | What s in a Semantic Network James F. Allen Alan M. Frisch Computer Science Department The University of Rochester Rochester NY 14627 Abstract Ever since Woods s What s in a Link paper there has been a growing concern for formalization in the study of knowledge representation. Several arguments have been made that frame representation languages and semantic-network languages are syntactic variants of the first-order predicate calculus FOPC . The typical argument proceeds by showing how any given frame or network representation can be mapped to a logically isomorphic FOPC representation. For the past two years we have been studying the formalization of knowledge retrievers as well as the representation languages that they operate on. This paper presents a representation language in the notation of FOPC whose form facilitates the design of a semantic-network-like reưiever. 1. Introduction We are engaged in a long-term project to consưuct a system that can partake in extended English dialogues on some reasonably well specified range of topics. A major part of this effort so far has been the specification of a knowledge representation. Because of the wide range of issues that we are trying to capture which includes the representation of plans actions time and individuals beliefs and intentions it is crucial to work within a framework general enough to accommodate each issue. Thus we began developing our representation within the first-order predicate calculus. So far this has presented no problems and we aim to continue within this framework until some problem forces us to do otherwise. Given this framework we need to be able to build reasonably efficient systems for use in die project. In particular the knowledge representation must be able to support the natural language understanding task. This requừes that certain forms of inference must be made. Within a general theorem-proving framework however those inferences desired would be lost within a wide range of .