fact: Definition order_axioms r s := [/\ (forall y x z, gle r x y -> gle r y z -> gle r x z), (forall x y, gle r x y -> gle r y x -> x = y), (forall x y, gle r x y -> (inc x s /\ inc y s)), (forall x, gle r x x <-> inc x s) & sgraph r].
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)