Fuzzy Set Operations
Contents
Definitions.
Universe of DiscourseThe Universe of Discourse is the range of all possible values for an input to a fuzzy system. Fuzzy SetA Fuzzy Set is any set that allows its members to have different grades of membership (membership function) in the interval [0,1]. SupportThe Support of a fuzzy set F is the crisp set of all points in the Universe of Discourse U such that the membership function of F is nonzero. Crossover pointThe Crossover point of a fuzzy set is the element in U at which its membership function is 0.5. Fuzzy SingletonA Fuzzy singleton is a fuzzy set whose support is a single point in U with a membership function of one.
Fuzzy Set Operations.

Union
 The membership function of the Union of two fuzzy sets A and B with membership functions and respectively is defined as the maximum of the two individual membership functions
The Union operation in Fuzzy set theory is the equivalent of the OR operation in Boolean algebra. 
Complement
 The membership function of the Complement of a Fuzzy set A with membership function is defined as

De Morgans law
, 
Associativity

Commutativity

Distributivity