Relaxation as a Platform for Cooperative Answering

Terry Gaasterland, Parke Godfrey and Jack Minker

Computer Science Department,
University of Maryland
College Park

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Responses to queries posed by a user of a database do not always contain the information desired. Database answers to a query, although they may be logically correct, can sometimes be misleading. Research in the area of cooperative answering for databases and deductive databases seeks to rectify these problems. We introduce a cooperative method called relaxation for expanding deductive database and logic programming queries. The relaxation method expands the scope of a query by relaxing the constraints implicit in the query. This allows the database to return answers related to the original query as well as the literal answers themselves. These additional answers may be of interest to the user. In section 1 we introduce the problem and method. In section 2 we give some background on the research done in cooperative answering. Section 3 discusses the relaxation method, a potental control strategy, and uses. Section 4 looks at a semantic counterpart to this notion. In section 5 we explore some of the control and efficiency issues. We enumerate open issues in section 6, and conclude in section 7. This work was supported by the Air Force Office of Scientific Research under grant number AFSOSR-91-0350. ^L Relaxation as a Platform for Cooperative Answering p. 1 of 21