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