neither a directed graph, nor a finite Boolean matrix, nor a Hasse diagram can be used to depict .

Properties of relations

Some important properties that a relation over a set may have are:

; [[Reflexive relation: for all , . For example, is a reflexive relation but is not.

; [[Irreflexive relation (or strict): for all , not . For example, is an irreflexive relation, but is not.

The previous 2 alternatives are not exhaustive; e.g., the red relation given in the diagram below is neither irreflexive,