Definition cmp_different_blocks (c: comparison) : abool :=
  match c with
  | Ceq => Maybe false
  | Cne => Maybe true
  | _   => Bnone
  end.

(* Specifications: *)
Lemma cmp_different_blocks_none: forall c, cmatch None (cmp_different_blocks c).
Lemma cmp_different_blocks_sound: forall c, cmatch (Val.cmp_different_blocks c) (cmp_different_blocks c).