Belief contraction without recovery

  title={Belief contraction without recovery},
  author={Sven Ove Hansson},
  journal={Studia Logica},
  • S. Hansson
  • Published 1 June 1991
  • Biology
  • Studia Logica
The postulate of recovery is commonly regarded to be the intuitively least compelling of the six basic Gärdenfors postulates for belief contraction. We replace recovery by the seemingly much weaker postulate of core-retainment, which ensures that if x is excluded from K when p is contracted, then x plays some role for the fact that K implies p. Surprisingly enough, core-retainment together with four of the other Gärdenfors postulates implies recovery for logically closed belief sets. Reasonable… 
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We discuss the rather special status of the postulate of "recovery" among the six basic postulates for theory contraction as formulated and studied by Alchourr6n, Gdirdenfors and the author. Our
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The authors investigate "partial meet contraction functions", which are defined to yield the intersection of some nonempty family of maximal subsets of the theory that fail to imply the proposition being eliminated, and basic properties of these functions are established.
On the logic of theory change: Safe contraction
A notion of “safe contraction” of a set of propositions is defined, it is shown that it satisfies the Gärdenfors postulates for contraction and thus can be represented as a partial meet contraction, and its properties are studied both in general and under various natural constraints.
Investigations into a Theory of Knowledge Base Revision
This paper formulates some desirable principles of knowledge revision, and investigates a new theory of revision that realizes these principles, and illustrates its application through examples and compare it with several other approaches.
Multiple contraction. A further case against Gärdenfors' principle of recovery
  • R. Niederée
  • Mathematics, Computer Science
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  • 1989
Theory contraction through base contraction