proposition: Lemma funenegN f : (\- f)^\- = f^\+.
proof: Proof. by apply/funext => x; rewrite /funeneg oppeK. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrnum ssrint interval finmap) mathcomp(mathcomp_extra boolp classical_sets fsbigop) mathcomp(functions cardinality set_interval) signed reals ereal topology normedtype sequences