Characterization of AGM Belief Contraction in Terms of Conditionals
Giacomo F. Bonanno · Electronic Proceedings in Theoretical Computer Science · 2023
We provide a semantic characterization of AGM belief contraction based on frames consisting of a Kripke belief relation and a Stalnaker-Lewis selection function.The central idea is as follows.Let K be the initial belief set and K ÷ φ be the contraction of K by the formula φ ; then ψ ∈ K ÷ φ if and only if, at the actual state, the agent believes ψ and believes that if ¬φ is (were) the case then ψ is (would be) the case.