The Virtues of Hesitation: Optimal Timing in a Non-Stationary World
研究了在环境随机变化、反应有成本且可能过时的情况下，如何根据变化的风险率（递增或递减）决定是否延迟反应，为决策系统引入延迟提供了理论依据。
In many economic, political, and social situations, circumstances change at random points in time, reacting is costly, and reactions appropriate to present circumstances may become inappropriate upon future changes, requiring further costly reaction. Waiting is informative if arrival of the next change has non-constant hazard rate. We identify two classes of situations: in the first, delayed reaction is optimal only when the hazard rate of further changes is decreasing; in the second, it is optimal only when the hazard rate of further changes is increasing. These results in semi-Markovian decision theory provide motivations for building delay into decision systems.