Hedge Algebra Based Type-2 Fuzzy Logic System and its Application to Predict Survival Time of Myeloma Patients

In this paper, we propose a method to construct hedge algebra based type-2 fuzzy logic systems (HA-T2FLS). In these fuzzy logic systems, the footprints of uncertainty (FOU) of type-2 fuzzy sets are optimized by genetic algorithm and the dispersion of data. The key ingredient of our system is the concept of centroid of hedge algebra based type-2 fuzzy sets. It is used in the type-reducing of the HA-T2FLS, and transforming interval type-2 fuzzy sets to hedge algebra based type-2 fuzzy sets. As an application, we show how hedge algebra based type-2 fuzzy logic systems can be used to predict survival time of myeloma patients. The results show that hedge algebra based type-2 fuzzy logic systems are more accurate than type-1 and interval type-2 fuzzy logic systems in this class of problems.