fact: Definition monotone_class := [/\ forall A, G A -> A `<=` D, G D, setD_closed & ndseq_closed].
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)