PUMA publications for /user/hotho/***%20properties%20folksonomyFri Jan 16 11:50:31 CET 2009Journal of Physics A: Mathematical and Theoretical22224016 (7pp)Folksonomies and clustering in the collaborative system CiteULike412008*** citeulike clustering dataset folksonomy network properties We analyze CiteULike, an online collaborative tagging system where users bookmark and annotate scientific papers. Such a system can be naturally represented as a tri-partite graph whose nodes represent papers, users and tags connected by individual tag assignments. The semantics of tags is studied here, in order to uncover the hidden relationships between tags. We find that the clustering coefficient can be used to analyze the semantical patterns among tags.