%0 Conference Paper %1 1506255 %A Wetzker, Robert %A Umbrath, Winfried %A Said, Alan %B ESAIR '09: Proceedings of the WSDM '09 Workshop on Exploiting Semantic Annotations in Information Retrieval %C New York, NY, USA %D 2009 %I ACM %K plsi recommender %P 25--29 %T A hybrid approach to item recommendation in folksonomies %U http://www.dai-labor.de/fileadmin/files/publications/wetzker_folksonomyrecommendation_esair2009_final.pdf %X In this paper we consider the problem of item recommendation in collaborative tagging communities, so called folksonomies, where users annotate interesting items with tags. Rather than following a collaborative filtering or annotation-based approach to recommendation, we extend the probabilistic latent semantic analysis (PLSA) approach and present a unified recommendation model which evolves from item user and item tag co-occurrences in parallel. The inclusion of tags reduces known collaborative filtering problems related to overfitting and allows for higher quality recommendations. Experimental results on a large snapshot of the delicious bookmarking service show the scalability of our approach and an improved recommendation quality compared to two-mode collaborative or annotation based methods.