proposition: Lemma greatest_nodup_prefix_intro' : forall l, exists m, l = greatest_nodup_prefix l ++ m.
proof: Proof. intro. ded (greatest_nodup_prefix_intro l). destruct H. exists nil. rewrite <- H. apply app_nil_end. decomp H. exists (x::x0). exact H0. Qed.
imports: CoLoR(ListUtil NatUtil RelMidex LogicUtil)