An Extension Of The Possibility Theory In View Of The Formalization Of Approximate Reasoning

Our aim is here to give some indications about the basis of a logic system in order to generalize the possibility theory in the following way : We want that each sentence receive a couple of confidence values. We call them degrees of obligation and eventuality, in order to translate the notion of truth by the halfsum of these values, and a notion that we can see as the imprecision given to this truth value : the diference eventuality - obligation which we shall call the unknown rather than uncertainty. In relation to the possibility theory, we whish to leave the general property max(ps(P), ps(P)) = 1 and then leave : nc(P) > 0 ps(P) = 1 and ps(P) < 1 nc(P) = 0 The aim of this extension is sitted in the tentation of modelising the degrees of truth and unknown, and their propagation when inferences, in the computing system about approximate reasoning. We would like that linguistics appreciations with vagueness such "perhaps true", "probably false", "true always three times on four..