fact: Definition pre_sup_leq u e (pf : e \In u) : pre_sup u <== pre_of e := fun h (pf1 : pre_sup u h) => pf1 e pf.
imports: mathcomp(ssreflect ssrbool ssrfun ssrnat eqtype seq) pcm(options axioms pred prelude) pcm(pcm unionmap heap) htt(domain)