Functional Polycentricity: A Formal Definition in Terms of Social Network Analysis

Polycentricity is often used descriptively with regard to a regional system of settlements, usually referred to as a polycentric urban region (PUR). Although presented in much of the literature as in essence a morphological concept, polycentricity possesses a functional element that receives less attention. Polycentricity is also seen as a normative concept. However, it has not been rigorously defined using formal techniques. This paper argues that defining polycentricity in terms of both morphology and function is possible by drawing on techniques originating in social network analysis. The paper sets out a formal definition and derivation of functional polycentricity based on these techniques, which is then extended to a derivation of an index of regional functional polycentricity. The paper sets out worked examples to show how the techniques described might be utilised. The paper closes with a discussion of issues that may arise when putting these definitions into practice.