Ltac freeze_tac L name :=
  eapply (freeze_SEP'' (map nat_of_Z L));
  first [solve [reflexivity] |
         match goal with
           | |- semax _ (PROPx _ (LOCALx _ (SEPx ((FRZL ?xs) :: _)))) _ _ =>
           let D := fresh name in
           set (D:=xs);
(*           hnf in D;*)
           change xs with (@abbreviate (list mpred) xs) in D;
           simpl nat_of_Z; unfold my_delete_nth
         end].Definition t := Z.Definition leb := Z.leb.

Theorem leb_total : forall a1 a2, Z.leb a1 a2 = true \/ Z.leb a2 a1 = true.