Set A: {a1, a2, a3}
Set B: {b1, b2, b3}

a1 - b1
a2 - b2
a3 - b3

a1 - b2
a2 - b1
a3 - b3

It's still a one to one relation, however, it's no longer static (or
maybe it never was, depending on your philosophy)