proposition: Lemma dec_inj_in : {in D &, {mono f : x y /~ x <= y}} -> {in D &, injective f}.
proof: Proof. exact: mono_inj_in. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)