IS THE SUCCESS OF FUZZY-LOGIC REALLY PARADOXICAL - TOWARD THE ACTUAL LOGIC BEHIND EXPERT-SYSTEMS

The formal concept of logical equivalence in fuzzy logic, while theore tically sound, seems impractical. The misinterpretation of this concep t has led to some pessimistic conclusions. Motivated by practical inte rpretation of truth values for fuzzy propositions, we take the class ( lattice) of all subintervals of the unit interval [0, 1] as the truth value space for fuzzy logic, subsuming the traditional class of numeri cal truth values from [0, 1]. The associated concept of logical equiva lence is stronger than the traditional one. Technically, we are dealin g with much smaller set of pairs of equivalent formulas, so that we ar e able to check equivalence algorithmically. The checking is done by s howing that our strong equivalence notion coincides with the equivalen ce in logic programming. (C) 1996 John Wiley & Sons, Inc.