proposition: Lemma integralB : \int[mu]_(x in D) (f1 \- f2) x = \int[mu]_(x in D) f1 x - \int[mu]_(x in D) f2 x.
proof: Proof. rewrite -[in RHS](@integralN _ _ _ _ _ f2); last exact: integrable_add_def. by rewrite -[in RHS]integralD//; exact: integrableN. 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