F. S. Gohari - Department of Industrial Engineering, K.N. Toosi University of Technology, Tehran, Iran
M.J. Tarokh - Department of Industrial Engineering, K.N.Toosi University of Technology, Tehran, Iran

Recommender systems have become fundamental applications in overloaded information domains like e-commerce. These systems aim to provide users with suggestions about items that are likely to be of their interest. Collaborative Filtering (CF) is one of the most successful approaches in recommender systems. Regardless of its success in many application domains, CF has main limitations such as sparsity, cold start, gray sheep and scalability problems. In order to overcome these limitations, hybrid CF systems have been used which combine CF with other recommendation approaches. This paper provides a comprehensive survey of hybrid CF systems; it also provides a classification for these systems,  explains their strengths or weaknesses and compares their performance in dealing with the main limitations of CF.

Recommender systems, collaborative filtering, hybrid collaborative, filtering systems