Lester Mackey

  1. The Asymptotics of Ranking Algorithms.

    Authors: Michael I. Jordan, John C. Duchi, Lester Mackey
    Subjects: Statistics
    Abstract

    We consider the predictive problem of supervised ranking, where the task is
    to rank sets of candidate items returned in response to queries. Although there
    exist statistical procedures that come with guarantees of consistency in this
    setting, these procedures require that individuals provide a complete ranking
    of all items, which is rarely feasible in practice. Instead, individuals
    routinely provide partial preference information, such as pairwise comparisons
    of items, and more practical approaches to ranking have aimed at modeling this
    partial preference data directly.

  2. Combinatorial clustering and the beta negative binomial process.

    Authors: Michael I. Jordan, Tamara Broderick, Lester Mackey, John Paisley
    Subjects: Methodology
    Abstract

    In this work, we establish novel connections between the Bayesian
    nonparametric clustering and featural paradigms by considering the problem of
    admixture modeling. We examine the Dirichlet process-and its unnormalized
    Poisson point process generation via the gamma process-on the traditional
    clustering side of Bayesian nonparametrics. On the featural side, we examine
    the beta process and introduce a new model, the beta negative binomial process
    (BNBP), for admixture modeling.

  3. Divide-and-Conquer Matrix Factorization.

    Authors: Michael I. Jordan, Ameet Talwalkar, Lester Mackey
    Subjects: Learning
    Abstract

    This work introduces SubMF, a parallel divide-and-conquer framework for noisy
    matrix factorization. SubMF divides a large-scale matrix factorization task
    into smaller subproblems, solves each subproblem in parallel using an arbitrary
    base matrix factorization algorithm, and combines the subproblem solutions
    using techniques from randomized matrix approximation. Our experiments with
    collaborative filtering, video background modeling, and simulated data
    demonstrate the near-linear to super-linear speed-ups attainable with this
    approach.

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