Tensor Fold-in Algorithms for Social Tagging Prediction

Social tagging predictions involve the co occurrence of users, items and tags. The tremendous growth of users require the recommender system to produce tag recommendations for millions of users and items at any minute. The triplets of users, items and tags are most naturally described by a 3D tensor, and tensor decomposition-based algorithms can produce high quality recommendations. However, each day, thousands of new users are added to the system and the decompositions must be updated daily in a online fashion. In this paper, we provide analysis of the new user problem, and present fold-in algorithms for Tucker, Para Fac, and Low-order tensor decompositions. We show that these algorithm can very efficiently compute the needed decompositions. We evaluate the fold-in algorithms experimentally on several datasets and the results demonstrate the effectiveness of these algorithms.