Relevancy transformation operators: Construction methods

This article deals with the construction of relevancy transformation (RET) operators for fuzzy systems. The notion of pseudo‐duality is introduced to obtain new RET operators, and t‐norms, t‐conorms, nullnorms, and uninorms are used in different ways for the same purpose. Finally, several other methods to construct new RET operators from old ones are pointed out. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 155–171, 2006.