关键词: 城市网络, 凝聚子群, QAP回归, 偏好依附, 流动空间

Abstract:

Cohesive subgroup constitutes a bridge connecting individual cities and urban network. This paper aims to analyze the cohesive subgroups and their mechanisms in the urban network in China. First, data on headquarter and branch locations of China's top 500 public companies in 2016 are subjected to ownership linkage model to approximate the urban network, resulting in a 294×294 valued urban network. Second, four measures of cohesive subgroup analysis, i.e. cliques, k-cores, lambda sets and core-periphery techniques are employed to generalize about the link strengths between cities. Finally, the influencing factors of the cohesive subgroups in the urban network are examined by using quadratic assignment procedure, and the mechanisms are explored under a conceptual framework of urban network growth. Three main findings are concluded. First, the four measures of cliques, k-cores, lambda sets and core-periphery techniques all indicate the presence of cohesive subgroups, revealing the hierarchical structure of link strengths in the urban network in China. The cohesive subgroups are mainly composed of core cities of urban agglomerations, and the cities in the eastern and central regions have more active economic ties compared to the cities in the western region. Second, key resources possessed by cities, such as economic scale, political resources, and knowledge capital, are important factors underlying the formation of cohesive subgroups. Links are more likely to occur between cities with larger economies, richer political resources and more intensive knowledge capital. Temporal distance, geographical location and path dependence also have a profound influence on the spatial pattern of cohesive subgroups. Third, network homophily and path dependence are the dynamic mechanisms underlying the development of cohesive subgroups, and the key resources and location advantages of cities will be further translated into network competitiveness. In the network environment, China's urban governance system and urbanization policies need to be adjusted accordingly. The Chinese government needs to promote network cooperation between cities on a larger spatial scale, and actively respond to the widening economic gap between cities under the network environment.

Key words: urban network, cohesive subgroup, QAP regression, preference attachment, space of flows