Interval Valued Versions of T-Conorms, Fuzzy Negations and Fuzzy Implications

Abstract

There exists infinitely many way to extend the classical prepositional connectives to the set [0,1] such that the behavior in their extremes are as in the classical logic. Still, is a consensus that it is not sufficient, demanding that these extensions also preserves some logical properties of the classical connectives. Thus, were introduced the notions of t-norms, t-conorms, fuzzy negations, and fuzzy implications. In a previous work, the authors generalize the t-norm notion to the set II = {[a, b] : 0 les a les b les 1}, named interval t-norms, and provided canonical constructions to obtain an interval t-norm which is the best interval representation of the t-norm. In this paper, we generalize the notions of t-conorm, fuzzy negation and fuzzy implication to the set I and provide canonical constructions to obtain their best interval representations. We will also provide a way to obtain: an interval fuzzy t-conorm from an interval t-norm and an interval fuzzy negation, an interval fuzzy implication from an interval t-norm, and an interval fuzzy negation from an interval fuzzy implication. We also prove several properties for this constructions.