ylfink@water.waterloo.edu (ylfink) (12/13/88)
DEPARTMENT OF COMPUTER SCIENCE
UNIVERSITY OF WATERLOO
SEMINAR ACTIVITIES
ARTIFICIAL INTELLIGENCE SEMINAR
- Wednesday, December 14, 1988
Mr. Scott D. Goodwin, Department of Computing Science,
University of Alberta, will speak on ``Temporal
Reasoning: What's the Problem Anyway?''.
TIME: 1:30 PM
ROOM: DC 1304
ABSTRACT
Much interest has been focused on nonmonotonic
reasoning in temporal domains since Hanks and McDermott
discovered that intuitive temporal representations give
rise to the multiple extension problem. In this talk,
nonmonotonic reasoning in temporal domains is
considered from the perspective of the Theorist
hypothetical reasoning framework. Theorist was
originally developed at the University of Waterloo and
now several researchers across Canada are actively
investigating its foundations and applicability.
The first part of the talk will describe the Theorist
framework. We then show how Theorist can be used to
represent temporal domains (in the case of discrete
time). We discuss the multiple extension problem and
how it arises in Theorist. One attempt to overcome
this problem, a theory preference scheme called the
chronological maximization of persistence (CMP), will
be examined. We show why this scheme is only
applicable under certain circumstances.
The final part of the talk is more speculative. It
describes a more robust approach to the multiple
extension problem currently under investigation. This
approach adopts the view that in many cases multiple
extensions arise because of failure to take into
account what the probabilists call conditioning
information. Finally we describe how some of the
problems for which CMP is not applicable can be
addressed using a theory preference criterion based on
Markov's principle.