Calculus of fuzzy if-then rules and its applications
Lotfi A. Zadeh · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1992
In contrast to classical logical systems, fuzzy logic is aimed at a formalization of modes of reasoning which are approximate rather than exact. Basically, a fuzzy logical system may be viewed as a result of fuzzifying a standard logical system. Thus, one may speak of fuzzy predicate logic, fuzzy modal logic, fuzzy default logic, fuzzy multivalued logic, fuzzy epistemic logic, etc. In this perspective, fuzzy logic is essentially a union of fuzzified logical systems, and precise reasoning may be viewed as a special case of approximate reasoning.