fact: Definition finI_from (I : choiceType) T (D : set I) (f : I -> set T) := [set \bigcap_(i in [set` D']) f i | D' in [set A : {fset I} | {subset A <= D}]].
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed