Spatial Competition with Heterogeneous Firms
构建了一个包含任意多家异质性企业的模型，研究企业如何在水平与垂直两个维度实现产品差异化，并证明在均衡精炼下所有经济结果唯一确定。核心发现是：企业的价格、市场份额和利润仅取决于市场平均边际成本，且生产率更高的企业地理上更孤立。
I model endogenous horizontal and vertical product differentiation with arbitrarily many heterogeneous firms. Firms are asymmetric in that they differ in their marginal costs. I prove that under an equilibrium refinement, all economically relevant firm outcomes are uniquely determined across all strict subgame perfect Nash equilibria. There are two central results. First, a firm's price, market share, and profit are independent of its neighbors' marginal costs, conditional on the average marginal cost in the market. Second, more productive firms are more isolated, all else equal. In particular, the distance between two firms is strictly decreasing in their average marginal cost. (c) 2008 by The University of Chicago. All rights reserved.