Posterior sampling for reinforcement learning: worst-case regret bounds

Shipra Agrawal; Randy Jia

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arXiv · 1705.07041

Posterior sampling for reinforcement learning: worst-case regret bounds

Shipra Agrawal·Randy Jia

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Abstract

We present an algorithm based on posterior sampling (aka Thompson sampling) that achieves near-optimal worst-case regret bounds when the underlying Markov Decision Process (MDP) is communicating with a finite, though unknown, diameter. Our main result is a high probability regret upper bound of $\tilde{O}(DS\sqrt{AT})$ for any communicating MDP with $S$ states, $A$ actions and diameter $D$. Here, regret compares the total reward achieved by the algorithm to the total expected reward of an optimal infinite-horizon undiscounted average reward policy, in time horizon $T$. This result closely matches the known lower bound of $\Omega(\sqrt{DSAT})$. Our techniques involve proving some novel results about the anti-concentration of Dirichlet distribution, which may be of independent interest.

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Shipra Agrawal, Randy Jia. 2017-05-19. Posterior sampling for reinforcement learning: worst-case regret bounds. https://arxiv.org/abs/1705.07041

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