Aggregation by exponential weighting, sharp PAC-Bayesian bounds and sparsity

  • Authors:
  • A. Dalalyan;A. B. Tsybakov

  • Affiliations:
  • LPMA, University of Paris 6, Paris cedex 05, France 75252;LPMA, University of Paris 6, Paris cedex 05, France 75252 and Laboratoire de Statistique, CREST, Malakoff cedex, France 92240

  • Venue:
  • Machine Learning
  • Year:
  • 2008

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Abstract

We study the problem of aggregation under the squared loss in the model of regression with deterministic design. We obtain sharp PAC-Bayesian risk bounds for aggregates defined via exponential weights, under general assumptions on the distribution of errors and on the functions to aggregate. We then apply these results to derive sparsity oracle inequalities.