Latent Factor Models with Additive Hierarchically-smoothed User Preferences
Items in recommender systems are usually associated with annotated attributes such as brand and price for products; agency for news articles, etc. These attributes are highly informative and must be exploited for accurate recommendation. While learning a user preference model over these attributes can result in an interpretable recommender system and can hands the cold start problem, it suffers from two major drawbacks: data sparsity and the inability to model random effects. On the other hand, latent-factor collaborative filtering models have shown great promise in recommender systems; however, its performance on rare items is poor. In this paper we propose a novel model LFUM, which provides the advantages of both of the above models. We learn user preferences (over the attributes) using a personalized Bayesian hierarchical model that uses a combination (additive model) of a globally learned preference model along with user-specific preferences. To combat we smooth these preferences over the item-taxonomy an efficient forward-filtering and backward-smoothing algorithm. Our inference algorithms can handle both attributes (e.g., item brands) and continuous attributes (e.g., prices). We combine the user preferences with the latent- models and train the resulting collaborative filtering system end- using the successful BPR ranking algorithm. In our experimental analysis, we show that our proposed model several commonly used baselines and we carry out an ablation study showing the benefits of each component of our model.