Reflexive property
A binary relation on a set is said to be reflexive or to have the reflexive property if for all .
For example, the relation of similarity on the set of triangles in a plane is reflexive: every triangle is similar to itself. However, the relation on the real numbers given by if and only if is not reflexive because does not hold for at least one real value of . (In fact, it does not hold for any real value of , but we only need the weaker statement to disprove reflexivity.)
See also
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