fact: Definition sup (f: T1-> T1) x z := [/\ T1nf z, (forall y, T1nf y -> y < x -> f y <= z) & (forall z', T1nf z' -> z' < z -> exists y, [&& T1nf y, y < x & z' < f y])].
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(fintype bigop)