A QUALITATIVE APPROACH TO FACE UNCERTAINTY IN DECISION-MODELS

Inaccurate determination, uncertainty, imprecision and ambiguity are o ften present in complex decision situations where decision aid is requ ested. Instead of reducing complexity via quantitative models of prefe rences, as traditional preference modeling does, it may be necessary t o represent these situations explicitly. There exist operational metho ds that face these problems, the principal reference being the partial comparability theory. The lack of an axiomatization however limits th e operational potentialities of this theory. In the paper an axiomatic foundation of the partial comparability theory is outlined based on a sound and complete four valued logic (the truth values ''true'', ''fa lse'', ''unknown'', ''contradictory'' are accepted). This logic is ext ended to the first order predicate calculus. Four basic preference rel ations are thus defined, namely: strict preference, weak preference, i ndifference and incomparability. The operational perspectives are disc ussed in the paper as some problems in multicriteria methods can be so lved in a much easier and natural way. Moreover non monotonic reasonin g devices could be built enhancing the potentialities of the theory.