عنوان مقاله [English]
A type-2 fuzzy set (or fuzzy-fuzzy set) is a fuzzy set that has fuzzy membership degrees. Such a set is useful wherein it is difficult to determine the exact membership degrees. A type-2 fuzzy system is robust against uncertainties that occur in fuzzy rules and system parameters. In this paper, first, The history of type-2 fuzzy theory which is developed during 25 recently years briefly is reviewed. Then type-2 fuzzy set and systems briefly are introduced and its basic terminologies are reviewed. Then perceptual computing based on type-2 fuzzy sets and methods of resolving difficulties computing of type-2 fuzzy systems are expressed. Finally, the type-2 fuzzy logic applications briefly are reviewed and conclusions and discussion on its future research fields have been done.