proposition: Lemma Exists_app_eq : forall P l1 l2, Exists P (l1++l2) = (Exists P l1 \/ Exists P l2).
proof: Proof. Proof using. intros. extens. induction l1; rew_list. { iff M [M|M]. { autos*. } { inverts~ M. } { autos*. } } { iff M [M|M]. { inverts* M. } { inverts M. { auto. } { applys* Exists_tail. } } { applys* Exists_tail. } } Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)