Contraction Based on Sentential Selection
Sven Ove Hansson · Journal of Logic and Computation · 2007
The properties of full meet contraction are investigated, and it is shown to be a useful building-block in the construction of composite contraction operators. This is followed by a detailed investigation of specified meet contraction, i.e. the operation ÷ such that K ÷ p = K ∼ f(p), where ∼ is full meet contraction and f is a function from sentences to sentences. A number of realistic examples of belief contraction are discussed, and it is shown how the properties of contraction differ according to how the sentence to be contracted is situated in the structure of the belief state. Some plausible properties of f are proposed, and it is shown how they correspond to properties of the contraction operator.