proposition: Lemma eqTleif x y C : x <= y ?= iff C -> C -> x = y.
proof: Proof. by move=> /eq_leif<-/eqP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)