proposition: Lemma caratheodory_measurable_setU A B : M A -> M B -> M (A `|` B).
proof: Proof. move=> mA mB X; apply/eqP; rewrite eq_le. by rewrite le_outer_measureIC andTb caratheodory_measurable_setU_le. 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)