val equal : t -> t -> bool
val positive : t -> set
val negative : t -> set
+ val inj_positive : set -> t
+ val inj_negative : set -> t
end
module Make (E : Sigs.Set) : S with type elt = E.elt and type set = E.t =
| CoFinite x -> x
| _ -> E.empty
+ let inj_positive t = Finite t
+ let inj_negative t = CoFinite t
end