Revision Operator

Belief Revision - Contraction
... The operators of revision and contractions are related by the Levi and Harper identities Eight postulates have been defined for contraction ... Whenever a revision operator satisfies the eight postulates for revision, its corresponding contraction operator satisfies the eight postulates for contraction, and vice versa ... If a contraction operator satisfies at least the first six postulates for contraction, translating it into a revision operator and then back into a ...

Belief Revision - Conditions Equivalent To The AGM Postulates
... The AGM postulates are equivalent to several different conditions on the revision operator in particular, they are equivalent to the revision operator ... Each revision operator satisfying the AGM postulates is associated to a set of preference relations, one for each possible belief base, such that the models of are exactly the minimal of all ... The revision operator and its associated family of orderings are related by the fact that is the set of formulae whose set of models contains all the minimal models of ...