Sébastien Gerchinovitz

  1. Adaptive and Optimal Online Linear Regression on L1-balls.

    Authors: Sébastien Gerchinovitz, Jia Yuan Yu
    Subjects: Machine Learning
    Abstract

    We consider the problem of online linear regression on individual sequences.
    The goal in this paper is for the forecaster to output sequential predictions
    which are, after T time rounds, almost as good as the ones output by the best
    linear predictor in a given L1-ball in R^d. We consider both the cases where
    the dimension d is small and large relative to the time horizon T. We first
    present regret bounds with optimal dependencies on the sizes U, X and Y of the
    L1-ball, the input data and the observations.

  2. Sparsity regret bounds for individual sequences in online linear regression.

    Authors: Sébastien Gerchinovitz
    Subjects: Machine Learning
    Abstract

    We consider the problem of online linear regression on arbitrary
    deterministic sequences when the ambient dimension $d$ can be much larger than
    the number of time rounds $T$. In this framework we prove deterministic online
    counterparts of the so-called sparsity oracle inequalities introduced in the
    stochastic setting in the past decade. They indicate that the task consisting
    in predicting almost as well as an unknown high-dimensional target vector is
    still statistically feasible if this target vector has only few non-zero
    coordinates.

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