let prop_icmp op x y =
match op with
| Eq -> F.p_icmp Formula.Ceq x y
| Ne -> F.p_icmp Formula.Cneq x y
| Lt -> F.p_icmp Formula.Clt x y
| Le -> F.p_icmp Formula.Cleq x y
| Ge -> F.p_icmp Formula.Cleq y x
| Gt -> F.p_icmp Formula.Clt y x
| _ -> assert false