%0 Journal Article
%@ 0295-5075      
%A Capocci, Andrea
%A Rao, Francesco
%A Caldarelli, Guido
%D 2008
%F eprints:1097
%I IOPscience
%J EPL (Europhysics Letters)
%K PACS: 89.75.Hc Networks and genealogical trees; 89.75.Fb Structures and organization in complex systems; 89.75.-k Complex systems
%N 2
%P 28006
%T Taxonomy and clustering in collaborative systems: the case of the on-line encyclopedia Wikipedia
%U http://eprints.imtlucca.it/1097/
%V 81
%X In this paper we investigate the nature and structure of the relation between imposed classifications and real clustering in a particular case of a scale-free network given by the on-line encyclopedia Wikipedia. We find a statistical similarity in the distributions of community sizes both by using the top-down approach of the categories division present in the archive and in the bottom-up procedure of community detection given by an algorithm based on the spectral properties of the graph. Regardless of the statistically similar behaviour, the two methods provide a rather different division of the articles, thereby signaling that the nature and presence of power laws is a general feature for these systems and cannot be used as a benchmark to evaluate the suitability of a clustering method.