ABSTRACT
Relations, or associations among objects, are of fundamental importance in the analysis of real-world systems. Mathematically, the concept is a very general one and has been discussed earlier in Chapter 2. There are many kinds of relations: order relations, equivalence relations, and other relations with various important properties. Relations are ubiquitous in mathematics, and their generalizations to fuzzy theory are important. This chapter presents some of these generalizations with an emphasis on binary relations, especially fuzzy equivalence relations, which generalize ordinary equivalence relations.
