<mathematics> A relation R is antisymmetric if,
for all x and y, x R y and y R x => x == y.
I.e. no two different elements are mutually related.
Partial orders and total orders are antisymmetric. If R is also symmetric (x R y => y R x) then x R y => x == y. I.e. different elements are not related.
(18 Apr 1995)