proposition: Lemma nneg_neq0_poweRB_def x r s : x != 0 -> (r >= 0)%R -> (s <= 0)%R -> x `^?(r +? - s).
proof: Proof. by move=> *; rewrite nneg_neq0_poweRD_def// oppr_ge0. 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