The second controller cannot communicate with the first controller and thus cannot observe either the original state x 0 {\displaystyle x_{0}} or the input u 1 {\displaystyle u_{1}} of the first controller.
第二個控制器不能和第一個控制器通訊，也無法觀察到原始狀態 x 0 {\displaystyle x_{0}} 或是第一個控制器的輸入 u 1 {\displaystyle u_{1}} 。