Backward
val neg : t -> t -> I.t Eva.Eval.or_bottom
val add : t -> t -> t -> (I.t * I.t) Eva.Eval.or_bottom
val sub : t -> t -> t -> (I.t * I.t) Eva.Eval.or_bottom
val mul : t -> t -> t -> (I.t * I.t) Eva.Eval.or_bottom
val div : t -> t -> t -> (I.t * I.t) Eva.Eval.or_bottom