On the relationship between preference and similarity-based approaches to possibilistic reasoning

Two main approaches to possibilistic reasoning with classical propositions have been proposed in the literature. The Dubois-Prade approach has a semantics based on a preference ordering in the set of possible worlds, whereas the semantics of Ruspini´s approach relies on the notion of similarity or resemblance between worlds. The basic notions of both approaches are presented. The correspondence between the two approaches is studied. It is shown that there exists a strong relationship between them. It is demonstrated that both approaches can be considered as particular cases of a more general framework of fuzzy reasoning that allows dealing with vague propositions