In this paper we investigate the effect of local interaction in a simple urban economics model. Agents interact with others if and only if their interaction benefit outweights their travel cost and therefore meet others only within finite geographic windows. We show that two or more cites may co-exist at the equilibrium provided that they are sufficiently distant. For any interaction surplus function, there exists a unique spatial equilibrium on not too large city supports. The population density within a city is determined by a second order advance-delay differential equation, whose solutions are fully characterized for linear interaction surplus functions. Numerical analyses show that more localized interactions yield flatter population density and land rents over larger extents of the city support. They do not give support to the idea that multiple subcenters can be caused by small and finite geographic windows of interaction.

在本文中，我们研究了在简单的城市经济学模型中本地互动的影响。当且仅当他们的交互收益超过了他们的差旅费用，并因此仅在有限的地理窗口内与其他人会面时，代理才与其他人交互。我们表明，如果两个或多个引用之间的距离足够远，则它们可以在平衡处共存。对于任何相互作用的剩余函数，在不太大的城市支撑上都存在一个独特的空间平衡。城市内的人口密度由二阶提前-延迟微分方程确定，该方程的解针对线性相互作用剩余函数进行了充分描述。数值分析表明，在更大范围的城市支持下，更多的局部相互作用产生了更平坦的人口密度和土地租金。