can a relation be symmetric and antisymmetric?
<answer> Yes <context> Partial and total orders are antisymmetric by definition. A relation can be both symmetric and antisymmetric (e.g., the equality relation), and there are relations which are neither symmetric nor antisymmetric (e.g., the preys on relation on biological species). Antisymmetry is different from asymmetry, which requires both antisymmetry and irreflexivity.