proposition: Lemma powRB x r s : (r == s) ==> (x != 0) -> x `^ (r - s) = x `^ r / x `^ s.
proof: Proof. by move=> ?; rewrite powRD ?subr_eq0// powRN. 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