fact: Record in_filter T (F : set_system T) := InFilter { prop_in_filter_proj : T -> Prop; prop_in_filterP_proj : F prop_in_filter_proj }.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed