proposition: Lemma ger_powR a : 0 < a <= 1 -> {homo powR a : x y /~ y <= x}.
proof: Proof. move=> /andP[a0 a1] x y xy. by rewrite /powR gt_eqF// ler_expR ler_wnM2r// ln_le0. Qed.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum matrix) mathcomp(interval rat) mathcomp(boolp classical_sets functions) mathcomp(mathcomp_extra) reals ereal signed topology normedtype landau sequences derive realfun itv convex