Reversing the Levi identity

  title={Reversing the Levi identity},
  author={Sven Ove Hansson},
  journal={Journal of Philosophical Logic},
  • S. Hansson
  • Published 1 December 1993
  • Philosophy
  • Journal of Philosophical Logic
The AGM (Alchourrón-GÄrdenfors-Makinson) model of belief change is extended to cover changes on sets of beliefs that arenot closed under logical consequence (belief bases). Three major types of change operations, namely contraction, internal revision, and external revision are axiomatically characterized, and their interrelations are studied. In external revision, the Levi identity is reversed in the sense that onefirst adds the new belief to the belief base, and afterwards contracts its… 
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  • Philosophy
    The Logic of Theory Change
  • 1989
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