adjoint vector space的用法和样例：
- The obtained optimal control law consists of analytical linear feedforward and feedback terms and a nonlinear compensation term which is the limit of the adjoint vector sequence.
- The optimal control law consists of an accurate linear feedback term and a nonlinear delay compensation term that is the limit of an adjoint vector sequence.
- The Derivative of a Map between Vector Spaces.
- We have discussed sum for subspace of vector space, and cannot popularize sum of subspace to infinitude.