Introduction
Published in John N. Mordeson, Davender S. Malik, Fuzzy Automata and Languages, 2002
John N. Mordeson, Davender S. Malik
The concepts of transformation semigroup, covering, cascade product, and wreath product play a prominent role in the study of automata [92]. In this chapter, we examine these ideas for fuzzy finite state machines. Some severe and interesting complications arise when introducing these ideas to the fuzzy setting. One of the concepts we introduce to overcome some of the problems that arise is that of a polysemigroup. Let P be a nonempty set and P(P) be the power set of P. Let * be a function of P×P into P(P)∖{∅}. Then (P,*) is called a polysemigroup, [39, 102], if and only if x*(y*z)=(x*y)*z∀x,y,z∈P. The obvious abuse of notation is explained as follows: If x∈P and A,B⊂P, then x*A denotes {x}*A, A*x denotes A*{x}, and A*B=∪a∈A,b∈Ba*b.