proposition: Lemma midtape_tape_local_cons_left t r1 r2 x : left t = r1 /\ tape_local t = x :: r2 <-> t = midtape r1 x r2.
proof: Proof. rewrite midtape_tape_local_cons. intuition subst; cbn; auto. Qed.
imports: Undecidability.Shared.Libs.PSL.Vectors.Vectors Undecidability.TM.TM