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The semantics of rational contractions

Giesl, Jürgen; Neumann, Ingrid


This paper is concerned with the revision of beliefs in the face
of new and possibly contradicting information. In the Logic of
Theory Change developed by Alchourron, Gärdenfors and Makinson
this nonmonotonic process consists of a contraction and an
expansion of a set of formulas. to achieve minimal change they
formulated widely accepted postulates that rational contractions
have to fulfill.

Contractions as defined by Alchourron, Gärdenfors and Makinson
only operate on deductively closed sets of Formulas. Therefore
they cannot be used in practical applications, eg. knowledge
representation, where only finitely representable sets can be

We present a semantical characterization of rational finite
contractions (the class of rational contractions maintaining
finite representability) which provides an insight into the true
nature of these operations. This characterization shows all
possibilities to define concrete functions possessing these

When regarding concrete contractions known from literature in the
light of our characterization we have found that they are all
defined according to the same semantical strategy of minimal
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Volltext §
DOI: 10.5445/IR/38694
Cover der Publikation
Zugehörige Institution(en) am KIT Fakultät für Informatik – Institut für Logik, Komplexität und Deduktionssysteme (ILKD)
Publikationstyp Buch
Publikationsjahr 1994
Sprache Englisch
Identifikator urn:nbn:de:swb:90-AAA386946
KITopen-ID: 38694
Erscheinungsvermerk Karlsruhe 1994. (Interner Bericht. Fakultät für Informatik, Universität Karlsruhe. 1994,29.)
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