proposition: Lemma integralE D f : \int_(x in D) f x = \int_(x in D) (f ^\+ x) - \int_(x in D) f ^\- x.
proof: Proof. by rewrite [in LHS]/integral funepos_restrict funeneg_restrict -!ge0_integralE. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrnum ssrint interval finmap) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality fsbigop ) signed reals ereal topology normedtype sequences real_interval esum measure lebesgue_measure numfun