unfold val2loc; intros. destruct v1; inv H. destruct n; inv H2.
destruct v2; inv H0. destruct n0; inv H1. auto.
Qed.

(* Specifications: *)
Lemma loc_eq_dec (l1 l2 : loc) : Decidable.decidable (l1=l2).
intros; case_eq (beq_nat l1 l2); intros.