Let A and B be fuzzy sets that A,B ⊆ U, u is any element (e.g. value) in the U universe: u ∈ U.
In general, the triple (i,u,n) is called De Morgan Triplet iff so that for all x,y ∈ [0, 1] the following holds true: (generalized De Morgan relation).
[2] The intersection of two fuzzy sets A and B is specified in general by a binary operation on the unit interval, a function of the form Axioms i1 up to i4 define a t-norm (aka fuzzy intersection).
[2] The union of two fuzzy sets A and B is specified in general by a binary operation on the unit interval function of the form Axioms u1 up to u4 define a t-conorm (aka s-norm or fuzzy union).
Aggregation operation on n fuzzy set (2 ≤ n) is defined by a function