proposition: Lemma bigcup_measurable F P : (forall k, P k -> measurable (F k)) -> measurable (\bigcup_(i in P) F i).
proof: Proof. move=> PF; rewrite bigcup_mkcond; apply: bigcupT_measurable => k. by case: ifP => //; rewrite inE; exact: PF. Qed.
imports: mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality fsbigop ) reals ereal signed topology normedtype sequences esum numfun HB(structures)