The union symbol ( ) denotes the union of two set s. It is commonly used in mathematics and engineering. Given two sets A and B, the union of A and B, written A B, is the set C of all elements that are in A or in B.
The diagram below illustrates set union. Sets A and B are denoted as circles (including their interiors). The set A B is represented by the entire shaded region.
Compare intersection symbol .
Also see Mathematical Symbols .