(** ** Lemmas about erased values*)

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

Lemma inj_value_erasure : forall (v1 v2 : val) (q : quantity), val_erasure v1 v2 -> memval_erasure_list (inj_value q v1) (inj_value q v2).