Zoubin Ghahramani, Katherine A. Heller
Inspired by “Google™ Sets”, we consider the problem of retrieving items from a concept or cluster, given a query consisting of a few items from that cluster. We formulate this as a Bayesian inference problem and de- scribe a very simple algorithm for solving it. Our algorithm uses a model- based concept of a cluster and ranks items using a score which evaluates the marginal probability that each item belongs to a cluster containing the query items. For exponential family models with conjugate priors this marginal probability is a simple function of sufﬁcient statistics. We focus on sparse binary data and show that our score can be evaluated ex- actly using a single sparse matrix multiplication, making it possible to apply our algorithm to very large datasets. We evaluate our algorithm on three datasets: retrieving movies from EachMovie, ﬁnding completions of author sets from the NIPS dataset, and ﬁnding completions of sets of words appearing in the Grolier encyclopedia. We compare to Google™ Sets and show that Bayesian Sets gives very reasonable set completions.