proposition: Lemma poweR_ge0 x r : 0 <= x `^ r.
proof: Proof. by move: x => [x| |]/=; rewrite ?lee_fin ?powR_ge0//; case: ifPn. 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