Kybernetika 49 no. 1, 149-163, 2013

On Some Properties of alpha-planes of Type-2 Fuzzy Sets

Zdenko Takáč


Some basic properties of $\alpha$-planes of type-2 fuzzy sets are investigated and discussed in connection with the similar properties of $\alpha$-cuts of type-1 fuzzy sets. It is known, that standard intersection and standard union of type-1 fuzzy sets (it means intersection and union under minimum t-norm and maximum t-conorm, respectively) are the only cutworthy operations for type-1 fuzzy sets. Recently, a similar property was declared to be true also for $\alpha$-planes of type-2 fuzzy sets in a few papers. Thus, we study under which t-norms and which \mbox{t-conorms} are intersection and union of the type-2 fuzzy sets preserved in the $\alpha$-planes. Note that understanding of the term $\alpha$-plane is somewhat confusing in recent type-2 fuzzy sets literature. We discuss this problem and show how it relates to obtained results.


fuzzy sets, type-2 fuzzy sets, $\alpha $-plane, intersection of type-2 fuzzy sets, union of type-2 fuzzy sets


03E72, 68T37


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