proposition: Lemma semi_additiveE : semi_additive mu = additive mu.
proof: Proof. rewrite propeqE; split=> [sa A mA tA n|+ A m mA tA UAm]; last by move->. by rewrite sa //; exact: bigsetU_measurable. 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)