Evolution of Spatial Structure of Commerce Center in Global City-Region: A Dynamic Agent-based Simulation

This paper presents an economic model of spatial structure of metropolitan commerce in city-region scenario based on monopolistic competition, scale economy, spatial cost, preference for variety, and product/service differentiations. However, this kind of traditional mathematic model is based on over-simplifying assumptions. Meanwhile, the equilibrium analysis is not suitable for dynamic research. To overcome the weakness of traditional deductive model and equilibrium analysis, the paper puts forward a new research approach to integrate economic deductive model with agent-based computational experiments for better understanding the evolutional process of metropolitan commerce. By using agent-based modeling and simulation, the spatial structure of metropolitan commerce can be observed dynamically indifferent scenarios. Therefore, instead of making nonlinear systems tractable by modeling complex building blocks with few interactions, we can make them understandable by modeling simple building blocks with many interactions among different agents in different districts based on our deductive economic model. Dynamic simulations show that:(1) The greater the gap of commercial fixed input between the new and old city zone is, the more imbalanced commercial space distribution would be, and more easy to form the core- periphery structure. (2) Due to diversified consumption preferences, inter-regional differences can change the business market share between the two region. (3) Commerce tends to gather in the place with location, population and fixed cost advantages, and improvements in traffic condition will accelerate the commercial spatial concentration. The related methodological issue such as integrating traditional economic model with agent-based geographical computation as well as empirical analysis and econometric test is also discussed.