proposition: Lemma lt_leif x y C : x <= y ?= iff C -> (x < y) = ~~ C.
proof: Proof. by move=> le_xy; rewrite lt_neqAle !le_xy andbT. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)