Transaction-based link strength prediction in a social network

The revolution of social networks and methods of analyzing them have attracted interest in many research fields. Predicting whether a friendship holds in a social network between two individuals or not, link prediction, has been a heavily researched topic in the last decade . In this paper we investigate a related problem, link strength prediction: how to assign ratings or strengths to friendship links. A basic approach would be matrix factorization applied to only friendship ratings. However, the existence of extensive transactions among users may be used for better predictions. We propose a new type of multiple-matrix factorization model for incorporating a transaction matrix. We derive gradient descent update equations for learning latent factors that predict values in the target rating matrix. Multiple-matrix factorization can be seen as a data fusion technique, that combines evidence from different sources. In the social network application, the target matrix contains friendship ratings and the evidence matrices specify transaction intensities between users. To evaluate the model, we introduce data from Cloob, a popular Iranian social network as well as synthetic data.