proposition: Lemma le_nat_spec : forall a b, reflect (le a b) (le_lt_bool a b).
proof: Proof. induction a; intros [|b]; simpl; try constructor; auto with arith. case (IHa ( b)); intros H; subst; constructor; auto with arith. Qed.
imports: ATBR(Common) Coq(Equality Program Sumbool Peano)