proposition: Lemma ordering_function_mono_weak (f : Ord -> Ord) (A B: Ensemble Ord) : ordering_function f A B -> forall a b, In A a -> In A b -> a <= b -> f a <= f b.
proof: Proof. destruct 1 as [H H0 H1 H2]. destruct 3. - subst b; left; auto with schutte. - right;auto. Qed.
imports: ZornsLemma(CountableTypes)