proposition: Lemma nondecn_inP : {in D, forall i, i.+1 \in D -> f i <= f i.+1} -> {in D &, {homo f : i j / i <= j}}.
proof: Proof. by apply: homo_leq_in Dconvex => //; apply: le_trans. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)