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From: phyllis@utcsrgv.UUCP (Phyllis Eve Bregman)
Newsgroups: ont.events
Subject: DCS Seminar Schedule
Message-ID: <1468@utcsrgv.UUCP>
Date: Mon, 6-Jun-83 11:26:50 EDT
Article-I.D.: utcsrgv.1468
Posted: Mon Jun  6 11:26:50 1983
Date-Received: Mon, 6-Jun-83 11:31:30 EDT
Organization: CSRG, University of Toronto
Lines: 21


	UofT Department of Computer Science Seminar Schedule for
		     the week of June 6th, 1983


Thursday, June 9th, 4:00 P.M., SF4101:  Dr. Moshe Y. Vardi, Computer Science
  Department, Stanford University, Stanford, California:  "On the semantics
  of updates in databases".


	ABSTRACT:  We suggest here a methodology for updating databases
	with integrity constraints and rules for deriving inexplicit
	information.  First we consider the problems of updating arbitrary
	theories by inserting into them or deleting from them arbitrary
	sentences.  The solution involves two key ideas:  when replacing
	an old theory by a new one we wish to minimize the change in the
	theory, and when there are several theories that involve minimal
	changes, we look for a new theory that reflects that ambiguity.
	The methodology is also adapted to updating databases, where
	different facts can carry different priorities, and to updating
	user views.