Relation R –1 from B to A can be defined
By interchanging the elements of all the ordered pairs of R.
Let A = {2, 3, 4} and B = {2, 6, 8}, and let R be the “divides” relation from A to B:
For every ordered pair (x, y) ∈ A × B, x R y ⇔ x | y.
Ordered pairs in R and R –1?
R –1 in words?
Directed graph
– Draw an arrow from each point of A to each related point.
– If a point is related to itself, a loop is drawn that extends out from the point and goes back to it.
– A subset of a Cartesian product of two sets
What about relations with n-tuple?