# 97-060/3 (1997-06-13)

Francesca Medda, Vrije Universiteit Amsterdam; Peter Nijkamp, Vrije Universiteit Amsterdam; Piet Rietveld, Vrije Universiteit Amsterdam

This paper focuses on the concept of network hierarchy as a descriptive device of organisational processes. In our research we have concentrated on a particular type of organisation: the spatial network system, in which interactive relations among the constituent parts are based upon the interconnectivity of the nodes. From this perspective, we conduct an illustrative network study through the examination of a simple network structure, where we compare two definitions of hierarchy. In the first definition, we examine the concept of hierarchy as a pyramidal structure based upon dominant and subordinate relations among nodes. The operational definition of this view of spatial hierarchy is realised by the accessibility matrix method. The second definition, which is the approach we have adopted, is grounded in Simon's concept of the Chinese boxes hierarchy; and we propose a new technique to construct spatial network hierarchies. From this perspective, our approach examines the membership of the nodes in the layered sub-networks which form the entire network. This allows us to more exhaustively define aframework of information about the network structure, such as, for instance, the analysis of the interchangeability and flexibility of the network nodes.