Abstract: Type-reduction is the key block in general type-2 fuzzy logic systems. This paper compares and analyzes the sum operation in discrete enhanced Karnik-Mendel (EKM) algorithms and the integral operation in continuous enhanced Karnik-Mendel (CEKM) algorithms. Based on the alpha- representation theory of general type-2 fuzzy sets, EKM algorithms are extended to perform the centroid type-reduction of general type-2 fuzzy logic systems. While computing the centroid type-reduced sets and the defuzzified values of general type-2 fuzzy logic systems, two computer simulation examples show that the calculation results of EKM algorithms can accurately approximate the CEKM algorithms, when the number of sampling of primary variables of centroid output GT2 FSs increases appropriately.

Key words: general type-2 fuzzy logic system, centroid, enhanced Karnik-Mendel algorithm, calculation accuracy, computer simulation