antisymmetric

Antisymmetric

$\forall x,y\in A:xRy\wedge yRx⟹x=y$ … if two elements are related both ways, they are the same element.
E.g.: $x\le y\wedge y\le x⟹x=y$ (which is not symmetric, e.g. $1\le 2$ but not $2\le 1$, and different from asymmetric, which is the opposite of symmetric $xRy⟹\neg (yRx)$).