Expressiveness of Epistemic Spaces for Iterated Belief Change Operators

Recently epistemic spaces have been introduced to formalize instantiations of iterated belief change operators and their translations from one concrete representation (epistemic space) to another. In this work, we build on these notions to deepen the understanding of iterated belief change and propose a general method for comparing the expressiveness of existing epistemic spaces. We introduce the notion of canonicity for epistemic spaces as a tool for identifying those that are sufficient, or necessary, to realize certain classes of iterated belief change operators. In particular, we give the canonical epistemic space (up to equivalence) that allows one to instantiate any iterated belief change operator.