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From: clarke@utcsri.UUCP (Jim Clarke)
Newsgroups: ont.events
Subject: UofT Comp. Sci. late announcement of AI seminar
Message-ID: <3484@utcsri.UUCP>
Date: Tue, 14-Oct-86 13:46:08 EDT
Article-I.D.: utcsri.3484
Posted: Tue Oct 14 13:46:08 1986
Date-Received: Tue, 14-Oct-86 13:52:40 EDT
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Organization: CSRI, University of Toronto
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                             LATE ANNOUNCEMENT

                      ARTIFICIAL INTELLIGENCE SEMINAR

               Tuesday, October 21, 3 p.m., in Galbraith 119

                          Dr. Vladimiar Lifschitz
                            Stanford University

                 "Default Reasoning and the Frame Problem"

     We apply McCarthy's theory of circumscription to formalizing reasoning
about action and change.  Formal theories of action include axioms describ-
ing the changes that take place in the world when actions are performed.
In addition, it is necessary to postulate that the only changes in the
state of the world are those that are implied by these axioms.  The problem
of formalizing this assumption is known as the "frame problem".  It has
long been recognized that this problem is closely related to the theory of
default reasoning, but attempts to apply existing formalizations of default
reasoning to the frame problem have led to significant technical difficul-
ties.  We show that these difficulties can be overcome if causality is
included in the theory as an additional primitive concept.
-- 

Jim Clarke -- Dept. of Computer Science, Univ. of Toronto, Canada M5S 1A4
              (416) 978-4058
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