A Perpetual Race to Stay Ahead
构建了两家企业在创新活动中动态竞争的模型，分析马尔可夫完美均衡结构，发现企业并非在势均力敌时竞争最激烈，而是在领先时加大投入以巩固优势，在落后时努力追赶以防被彻底超越。
This paper presents a model of dynamic competition between two firms that repeatedly engage in an innovative activity. The state of competition—measured by the difference between the number of innovations introduced by the firms—evolves stochastically according to their effort level. The structure of Markov perfect equilibria is identified. It is generally not true that competition is fiercest when firms are closest. Rather, firms invest under two distinct circumstances: while sufficiently ahead, to outstrip their rival and secure a durable leadership; while behind, to regain leadership and prevent the situation from worsening to the point where their rival outstrips them.