A Sequential Model of R&D Investment Over an Unbounded Time Horizon
构建了一个序列研发投资的马尔可夫模型，分析成功企业在后续研发中的优势如何影响投资决策，发现自由进入会导致过度竞争和过度投资，并提出限制专利期限、补贴连续成功企业及征收进入税的三部分政策来纠正市场失灵。
A Markov model of sequential R&D investment, where successful firms are assumed to have an advantage in related follow-on R&D, is formulated and a solution approach is given. Under this assumption, profit maximizing firms must consider the effect of R&D investments on their future market position as well as the direct monetary returns from innovation. Under certain conditions, free entry is shown to lead to excessive competition and overinvestment by the firms. This market failure can be corrected through a three-part policy of restricted patent lives, subsidies to firms for consecutive successes, and entry taxes. In addition to these policy conclusions, the modeling and solution approaches presented here provide a framework for further research efforts to incorporate market position into project selection and budget allocation models.