The SCOT(Social Semantic Cloud Of Tags) ontology is to semantically represent the structure and semantics of a collection of tags and to represent social networks among users based on the tags.
F. Belém, E. Martins, T. Pontes, J. Almeida, and M. Gonçalves. Proceedings of the 34th international ACM SIGIR conference on Research and development in Information Retrieval, page 1033--1042. New York, NY, USA, ACM, (2011)
S. Rendle, and L. Schmidt-Thieme. Proceedings of the third ACM international conference on Web search and data mining, page 81--90. New York, NY, USA, ACM, (2010)
C. Musto, F. Narducci, P. Lops, and M. de Gemmis. E-Commerce and Web Technologies, volume 61 of Lecture Notes in Business Information Processing, page 13--23. Berlin/Heidelberg, Springer, (2010)