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talk announcement Jim Delgrande

 The Database and Artificial Intelligence Group cordially invites you to the
 following talk:
 Speaker: James Delgrande  (joint work with Pavlos Peppas)
School of Computing Science
Simon Fraser University
Burnaby, B.C. Canada

   DATE:   Monday, 5. november 2012
 TIME:   16:00
   VENUE:  Seminarroom Gödel         (Favoritenstrasse 9-11, ground floor)
   TITLE: Revising Horn Theories

This talk addresses belief revision where the underlying logic is that
governing Horn clauses.
It proves to be the case that classical (AGM) belief revision doesn't
immediately generalise to the Horn case.
In particular, a standard construction based on a total preorder over
possible worlds may violate the accepted (AGM) postulates.
Conversely, Horn revision functions in the obvious extension to the AGM
approach are not captured by total preorders over possible worlds.
We address these difficulties by first restricting the semantic construction
to ``well behaved'' orderings;
and second, by augmenting the revision postulates by an additional postulate.
This additional postulate is redundant in the AGM approach but not in the
the Horn case.
In a representation result we show that these two approaches coincide.
Arguably this work is interesting for several reasons.
It extends AGM revision to inferentially-weaker Horn theories;
hence it sheds light on the theoretical underpinnings of belief change, as
well as generalising the AGM paradigm.
Thus, this work is relevant to revision in areas that employ Horn
clauses, such as deductive databases and logic programming, as well as areas
in which inference is weaker than classical logic, such as in description

 With kind support of the Wolfgang Pauli Institut (WPI) and VCLA.

 Beatrix Forsthuber


Beatrix Forsthuber
Institut für Informationssysteme E 184
Favoritenstraße 9-11
1040 Wien
DVR-Nummer: 0005886
Tel.: +43-1-58801-18403
Fax:  +43-1-58801-918403
mail: forst@dbai.tuwien.ac.at