Similarity and equivalence of epistemic states

Epistemic states is an important model introduced by Bochman for nonmonotonic inference and belief change. Taking Epistemic States as the object, a notion of similarity is presented. In order to explore the relationship between similarity and the reasoning behaviors of epistemic states, a new notion called quasi-skeptically equivalence and an operator par(.) over epistemic states were introduced. The main results show that any pair of pure finite epistemic states are quasi-skeptically equivalent if and only if their par-images are similar.