Specification of the world city network

World cities are generally deemed to form an urban system or city network b ut these are never explicitly specified in the literature. In this paper th e world city network is identified as an unusual form of network with three levels of structure: cities as the nodes, the world economy as the suprano dal network level, and advanced producer service firms forming a critical s ubnodal level. The latter create an interlocking network through their glob al location strategies for placing offices. Hence, it is tile advanced prod ucer service firms operating through cities who are the prime actors in wor ld city network formation. This process is formally specified in terms of f our inter city relational matrices-elemental. proportional, distance, and a symmetric. Through this specification it becomes possible to apply standard techniques of network analysis to world cities for the first time. In a sh ort conclusion the relevance of this world city network specification for b oth theory and policy-practice is briefly discussed.