Introducing Triple Play for Improved Resource Retrieval in Collaborative Tagging Systems Rabeeh Ayaz Abbasi and Steffen Staab Department of Computer Science, University of Koblenz-Landau, Koblenz, Germany {abbasi,staab}@uni-koblenz.de http://isweb.uni-koblenz.de/ Abstract. Collaborative tagging systems (like Flickr, del.icio.us, citeu- like, etc.) are becoming more popular with passage of time. Users share their resources on tagging systems, and add keywords (called tags) to these resources. Users can search resources using these tags. But as the user gives more tags for search, he might not get sufficient search results, because the resources might not be tagged with all the related tags. We introduce the method Triple Play, which smoothes the tag space by user space for improved retrieval of resources. As a part of Triple Play, we also propose two new vector space models for collaborative tag- ging systems, SmoothVSM Dense and SmoothVSM Sparse. These vector space models exploit the user-tag co-occurrence relationship to overcome the problem of missing information in tagging systems. Finally we apply Latent Semantic Analysis to different vector space models and analyze the results. Initial experimentation show that using additional informa- tion available in tagging systems helps in improving search in tagging systems. 1 Introduction Collaborative tagging systems provide their users an easy mechanism to store re- sources (like photos, bookmarks, publications) and add tags (keywords) to these resources. For example, a user can upload his photo of a trip to the beach of “St. Petersburg, Russia” to Flickr and tag it with petersburg and beach. He can search for the tags petersburg and beach to see this photo and other photos which are tagged with same tags by him or other users. Although tags provide an easy way to search resources, but they are only sparsely available. Many resources might not have all the relevant tags, and do not appear in relevant searches. If a user searches using less number of tags, he might get many undesired results, and if he provides many tags, he might a get few or no search results. Table 1 shows the number of search results for different tags searched on Flickr 1 web- site. Queries in table 1 assume boolean AND operator between the tags. It is obvious from Table 1 that as the number of tags in query increase, number of 1 http://www.flickr.com/search/?m=tags