proposition: Lemma measure_bigsetU_ord n (P : {pred 'I_n}) (F : 'I_n -> set T) : (forall i : 'I_n, measurable (F i)) -> trivIset setT F -> mu (\big[setU/set0]_(i < n | P i) F i) = (\sum_(i < n | P i) mu (F i))%E.
proof: Proof. by move=> mF tF; rewrite measure_bigsetU_ord_cond//; apply: sub_trivIset tF. 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)