Relation on Set A and Inverse Relation

Relation on Set A
A relation from A to A i.e., a subset of A×A, is called a relation on set A.

Inverse relation
When a relation R is from set A to set B, a relation from set B to set A denoted by R^-1 is the inverse of R. That is if R is a set of (a,b), then R^-1 is a set of (b,a).

In the case Domain of relation R = Range of relation R^-1

Range of relation R = Domain of relation R^-1