Proof using.
unfold good_op_move.
intuition eauto.
Qed.

(* Specifications: *)
Lemma not_good_op_move_OI :
forall k k',
good_op_move (O k) (I k') -> False.
Lemma good_op_move_good_move_IO :
forall k k',
good_op_move (I k) (O k') ->
good_move (IRI k) (IRO k').