In th is p ap er we stu d y two c lasses of im p rec ise p revisions, wh ic h we term ed c onvex and c entered c onvex p revisions, in th e f ram ework of Walley ’s th eory of im p rec ise p revisions. We sh ow th at c onvex p revisions are related with a c onc ep t of c onvex natu ral estension, wh ic h is u sefu l in c orrec ting a larg e c lass of inc onsistent im p rec ise p rob ab ility as...

Several forms of iterable belief change exist, differing in the kind and its strength: some operators introduce formulae, others remove them; add formulae unconditionally, only as additions to previous beliefs; relative current situation, all possible cases. A sequence changes may involve several them: for example, first step is a revision, second contraction third refinement beliefs. The ten c...

Theories of rational belief revision recently proposed by Alchourrón, Gärdenfors, Makinson, and Nebel illuminate many important issues but impose unnecessarily strong standards for correct revisions and make strong assumptions about what information is available to guide revisions. We reconstruct these theories according to an economic standard of rationality in which preferences are used to se...