fact: Definition finI (I : choiceType) T (D : set I) (f : I -> set T) := forall D' : {fset I}, {subset D' <= D} -> \bigcap_(i in [set i | i \in D']) f i !=set0.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed