The Realizability of Revision and Contraction Operators in Epistemic Spaces

TL;DR

This paper investigates the conditions under which belief revision and contraction operators can be realized in epistemic spaces, highlighting the special case of linear change operators as canonical realizations.

Contribution

It characterizes the realizability of AGM revision and contraction operators in epistemic spaces and introduces linear change operators as a canonical realization when realizable.

Findings

AGM revision and contraction are only realizable in precisely determined epistemic spaces.

Linear change operators are a special class of maxichoice operators.

When realizable, linear change operators serve as canonical realizations.

Abstract

This paper studies the realizability of belief revision and belief contraction operators in epistemic spaces. We observe that AGM revision and AGM contraction operators for epistemic spaces are only realizable in precisely determined epistemic spaces. We define the class of linear change operators, a special kind of maxichoice operator. When AGM revision, respectively, AGM contraction, is realizable, linear change operators are a canonical realization.