proposition: Lemma summable_addrC (S1 S2 : T -> R) : summable (S1 \+ S2) -> summable (S2 \+ S1).
proof: Proof. by apply/eq_summable => x; rewrite /= addrC. Qed.
imports: mathcomp(all_ssreflect all_algebra) mathcomp.classical(boolp) xfinmap ereal reals discrete realseq mathcomp.classical(classical_sets functions mathcomp_extra) topology