Set subset union. A B x x A x B Example 1. A relation that is reflexive symmetric and transitive is called an equivalence relation.
The union of sets A and B denoted by A B is the set defined as.
Definition Union. A relation that is reflexive symmetric and transitive is called an equivalence relation. X Z x 2 m 1 m Z mathbf color purple x in mathbb Zmid x 2m 1 m in mathbb Z x Z x 2m1 m Z. The items are called the MEMBERS or ELEMENTS of the set.