Model selection in reinforcement learning

  • Authors:
  • Amir-Massoud Farahmand;Csaba Szepesvári

  • Affiliations:
  • Department of Computing Science, University of Alberta, Edmonton, Canada T6G 2E8;Department of Computing Science, University of Alberta, Edmonton, Canada T6G 2E8

  • Venue:
  • Machine Learning
  • Year:
  • 2011

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Abstract

We consider the problem of model selection in the batch (offline, non-interactive) reinforcement learning setting when the goal is to find an action-value function with the smallest Bellman error among a countable set of candidates functions. We propose a complexity regularization-based model selection algorithm, $\ensuremath{\mbox{\textsc {BErMin}}}$, and prove that it enjoys an oracle-like property: the estimator's error differs from that of an oracle, who selects the candidate with the minimum Bellman error, by only a constant factor and a small remainder term that vanishes at a parametric rate as the number of samples increases. As an application, we consider a problem when the true action-value function belongs to an unknown member of a nested sequence of function spaces. We show that under some additional technical conditions $\ensuremath{\mbox{\textsc {BErMin}}}$ leads to a procedure whose rate of convergence, up to a constant factor, matches that of an oracle who knows which of the nested function spaces the true action-value function belongs to, i.e., the procedure achieves adaptivity.