Preferential attachment in the growth of social networks: the case of Wikipedia

Preferential attachment in the growth of social networks: the case of Wikipedia1 2,1 3 2 2 2 3,1A. Capocci, V. D. P. Servedio, F. Colaiori, L. S. Buriol, D. Donato, S. Leonardi, and G. Caldarelli1Centro Studi e Ricerche E. Fermi, Compendio Viminale, Roma, Italy2Dipartimento di Informatica e Sistemistica, Universit`a di Roma “La Sapienza”, Via Salaria 113, 00198 Roma, Italy3CNR-INFM(SMC) Istituto dei Sistemi Complessi and Dipartimento di Fisica,Universit`a di Roma “La Sapienza”, Piazzale Aldo Moro 2, 00185, Roma, Italy(Dated: February 2, 2008)We present an analysis of the statistical properties and growth of the free on-line encyclopediaWikipedia. By describingtopics byverticesand hyperlinksbetween themas edges, we can representthis encyclopedia as a directed graph. The topological properties of this graph are in close analogywith that of the World Wide Web, despite the very different growth mechanism. In particular wemeasure a scale–invariant distribution of thein– and out– degree and we are able to reproducethesefeatures by means of a simple statistical model. As a major consequence, Wikipedia growth canbe described by local rules such as the preferential attachment mechanism, though users can actglobally on the network.PACS numbers: : 89.75.Hc, 89.75.Da, 89.75.FbStatistical properties of social networks has become a Wikipedia is an intriguing research object from a so-major research topic in statistical physics of scale–free ciologist’s point of view: ...