A binary relation RRR on a set XXX (i.e. a subset of X×XX \times XX×X) is reflexive if it relates every x∈Xx \in Xx∈X to itself. That is, for all x∈Xx \in Xx∈X, (x,x)∈R(x,x) \in R(x,x)∈R.
Wikidata ID: Q621850