Enhancing Collaborative Filtering with Friendship Information Liliana Ardissono, Maurizio Ferrero, Giovanna Petrone, Marino Segnan Dipartimento di Informatica Università di Torino Torino, Italy {liliana.ardissono, giovanna.petrone, marino.segnan}@unito.it maurizio.ferrero@di.unito.it ABSTRACT With the convergence of social networks and recommender systems, new recommender algorithms have been explored, that combine observations on item selection with an analysis of social relations among people. Concerning collaborative filtering approaches, we test the impact of integrating a measure of common friendship, in order to capture the intuition that socially related groups of people tend to have similar tastes. An experiment on the Yelp dataset shows that using preference information derived from the commonalities of interests in networks of friends achieves higher accuracy than item-to-item and other collaborative filtering algorithms. Keywords: Recommender systems, collaborative filtering, homophily and social networks