(** ** Lemmas about erased values*)

  Definition isDefined v :=
    match v with
    | Vundef => false
    | _ => true
    end.

Lemma val_erasure_mul_result: forall v1 v2 v1' v2' v, val_erasure v1 v1'-> val_erasure v2 v2' -> Val.mul v1 v2 = v -> isDefined v -> Val.mul v1' v2' = v.