sig
type t
val fprint : Format.formatter -> t -> unit
val order : t -> t -> bool
val top : t
val bottom : t
val join : t -> t -> t
val meet : t -> t -> t
val widening : t -> t -> t
val sem_itv : int -> int -> t
val sem_plus : t -> t -> t
val sem_minus : t -> t -> t
val sem_times : t -> t -> t
val sem_div : t -> t -> t
val sem_guard : t -> t
val backsem_plus : t -> t -> t -> t * t
val backsem_minus : t -> t -> t -> t * t
val backsem_times : t -> t -> t -> t * t
val backsem_div : t -> t -> t -> t * t
end