Richard Bellman, 1950s, 最优化理论:
An Optimal policy has the property that whatever the initial state and initial decision are, the remaining decisions must constitute an optimal policy with regard to the state resulting from the first decision.
→The best time to plant a tree is 20 years ago. The second best time is now.
例:无人机高度控制
目标:从地面升到10m,时间最短

