A theoretical framework for evolutionary economic geography: industrial dynamics and urban growth as a branching process
提出一个理论框架，将经济发展视为产品创新的演化分支过程，解释企业规模与城市规模分布的形成，并强调多样性带来的收益（范围经济与雅各布斯外部性）是路径依赖和城市专业化的核心反馈机制。
We propose a framework that specifies the process of economic development as an evolutionary branching process of product innovations. Each product innovation provides a growth opportunity for an existing firm or a new firm, and for an existing city or a new city. One can then obtain both firm size and city size distributions as two aggregates resulting from a single evolutionary process. Gains from variety at the firm level (economies of scope) and the urban level (Jacobs externalities) provide the central feedback mechanism in economic development generating strong path dependencies in the spatial concentration of industries and the specialization of cities. Gains from size are also expected, yet these are ultimately bounded by increasing wages. The contribution of our framework lies in providing a microfoundation of economic geography in terms of the interplay between industrial dynamics and urban growth. The framework is sufficiently general to investigate systematically a number of stylized facts in economic geography, while at the same time it is sufficiently flexible to be extended such as to become applicable in more specific micro-contexts. A number of extensions related to the concepts of knowledge spillover and lock-in, are also discussed.