-cases l [ #m ]
-[ <path_head_d_sn <height_d_sn <depth_d_sn //
-| <path_head_m_sn <height_m_sn <depth_m_sn //
-| <path_head_L_sn <height_L_sn <depth_L_sn
+cases l [ #k ]
+[ <path_head_d_dx <height_d_dx <depth_d_dx <IH //
+| <path_head_m_dx <height_m_dx <depth_m_dx //
+| <path_head_L_dx <height_L_dx <depth_L_dx