Bipolar Possibilistic Representations
نویسندگان
چکیده
Recently, it has been emphasized that the possibility theory framework allows us to dis tinguish between i) what is possible because it is not ruled out by the available knowledge, and ii) what is possible for sure. This distinc tion may be useful when representing knowl edge, for modelling values which are not im possible because they are consistent with the available knowledge on the one hand, and values guaranteed to be possible because re ported from observations on the other hand. It is also of interest when expressing prefer ences, to point out values which are positively desired among those which are not rejected. This distinction can be encoded by two types of constraints expressed in terms of necessity measures and in terms of guaranteed possibil ity functions, which induce a pair of possibil ity distributions at the semantic level. A con sistency condition should ensure that what is claimed to be guaranteed as possible is indeed not impossible. The present paper investi gates the representation of this bipolar view . , mcluding the case when it is stated by means of conditional measures, or by means of com parative context-dependent constraints. The interest of this bipolar framework, which has been recently stressed for expressing prefer ences, is also pointed out in the representa tion of diagnostic knowledge.
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