fact: Definition filter_from {I T : Type} (D : set I) (B : I -> set T) : set_system T := [set P | exists2 i, D i & B i `<=` P].
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed