proposition: Lemma itau2_app {X : Type} {P : stack X} A B : itau2 P (A++B) = itau2 P A ++ itau2 P B.
proof: Proof. induction A; simpl; auto; rewrite <- app_assoc; simpl; f_equal; auto. Qed.
imports: List Undecidability.PCP.PCP Undecidability.PCP.Util.Facts Undecidability.Synthetic(Definitions DecidabilityFacts EnumerabilityFacts MoreEnumerabilityFacts ListEnumerabilityFacts) Coq.Init.Wf Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list utils_nat finite)