proposition: Lemma not_right : forall (p:key) (v':data), Key.le p n -> ~ occ v' p t2.
proof: Proof. intros p v' H; elim min_r. intros H0 H1; absurd (Key.lt n p); eauto with searchtrees. apply M.le_not_lt; assumption. Qed.
imports: Relations List ZArith Arith