proposition: Theorem lt_m1_r : forall n m, n < m -> m < 0 -> n < -1.
proof: Proof. intros n m H1 H2. apply lt_le_pred in H2. setoid_replace (P 0) with (-1) in H2. - now apply lt_le_trans with m. - apply eq_opp_r. now rewrite one_succ, opp_pred, opp_0. Qed.
imports: ZMul