In
1965
Lotfi Zadeh
introduced
Fuzzy Sets, in 1973 he introduced Fuzzy Logic. The former refers to an
extension of classical Set Theory in such a way that, given a set A, an element can belong only partially to
A. The latter is a kind of many-valued logic.
The phrase fuzzy logic has nowadays, however, several meanings.
Usually one distinguishes between fuzzy logic in broad sense and fuzzy
logic in narrow sense. A pleasantry way is to say that former is more
fuzzy than logic while the
latter is more logic than fuzzy. Seriously speaking, fuzzy logic in
broad sense has a multitude of industrial application, in particular in
control. A comprehensive description on what is going on in
Fuzzy Logic in broad sense can be found e.g. here, while
the main entrance to fuzzy logic in narrow sense is here.