Fuzzy control
By the expression "Fuzzy logic" one denotes several topics which are related with the notion of fuzzy set defined in 1965 by Lotfi Zadeh. The idea is that we can represent the extension of a vague property by a generalized characteristic function in which truth values in the interval [0,1] are admitted.
We have to distinguish two possible interpretations of the expression "fuzzy logic". The first one is given by people interested to applications and to an informal utilization of the notion of fuzzy subset. In such a case should be better expressions as "fuzzy logic in board sense" or theory of "fuzzy subset".
Another interpretation is given by people which consider fuzzy logic as a chapter of formal logic, more precisely of multi-valued logic. In such a case one uses the expression "fuzzy logic in narrow sense" or "fuzzy logic in narrow sense".