Lattices of Fuzzy Subgroups

Many results concerning relationships between classes of crisp subsets can be carried over to similar relationships between classes of fuzzy subsets. The purpose of the next few sections is to provide a framework for transferring crisp results into fuzzy results when such a transference is possible. This is accomplished by the presentation of a suitable metatheorem. The results of the first four sections of this chapter are mainly from [15, 16].