fact: Definition additive2 := forall A B, measurable A -> measurable B -> A `&` B = set0 -> mu (A `|` B) = mu A + mu B.
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)