fact: Definition sigma_additive := forall F, (forall i : nat, measurable (F i)) -> trivIset setT F -> (fun n => \sum_(0 <= i < n) mu (F i)) @ \oo --> mu (\bigcup_n F n).
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)