2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/30995A vast and interesting family of natural semantics for belief revision is defined. Suppose one is given a distance d between any two models. One may then define the revision of a theory K by a formula a as the theory defined by the set of all those models of a that are closest, by d, to the set of models of K. This family is characterized by a set of rationality postulates that extends the AGM postulates. The new postulates describe properties of iterated revisions.Preliminary version presented at TARK '96Artificial IntelligenceI.2.3text