proposition: Lemma infinite_diff P Q : infinite (diff P Q) -> infinite P.
proof: Proof. intro P_Q_inf. intro P_fin. apply P_Q_inf. apply finite_diff. hyp. Qed.
imports: Coq(Basics Morphisms Setoid Lia) CoLoR(ClassicUtil IotaUtil EpsilonUtil LogicUtil SetUtil FinSet FunUtil BoundNat IotaUtil EpsilonUtil)