Defining Membership Functions

The chapter presents basic concepts and methods used in defining membership functions of fuzzy sets. Usual problems of fuzzy set applications connected with the universe of discourse, shape, and accuracy of membership functions as well as with their acquisition are discussed. An example of a fuzzy set application to a medical score test modelling is given. In the example a modified Takagi-Sugeno algorithm of fuzzy identification is described. Conclusions about present customs and suggestions of future trends in defining membership functions close the study.