proposition: Lemma in_conc : forall u n (cs : Caps n), Vin u (conc cs) -> exists c, Vin c cs /\ Vin u (aliens c).
proof: Proof. induction cs; simpl; intros. contr. assert (Vin u (aliens h) \/ Vin u (conc cs)). apply Vin_app. hyp. destruct H0. exists h. auto. assert (exists c, Vin c cs /\ Vin u (aliens c)). apply IHcs. hyp. destruct H1 as [c]. exists c. intuition. Qed.
imports: CoLoR(LogicUtil ACalls ATrs VecUtil ListUtil NatUtil RelUtil)