Super-Exponential Regret for UCT, AlphaGo and Variants

Laurent Orseau; Remi Munos

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arXiv · 2405.04407

Super-Exponential Regret for UCT, AlphaGo and Variants

Laurent Orseau·Remi Munos

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Abstract

We improve the proofs of the lower bounds of Coquelin and Munos (2007) that demonstrate that UCT can have $\exp(\dots\exp(1)\dots)$ regret (with $\Omega(D)$ exp terms) on the $D$-chain environment, and that a `polynomial' UCT variant has $\exp_2(\exp_2(D - O(\log D)))$ regret on the same environment -- the original proofs contain an oversight for rewards bounded in $[0, 1]$, which we fix in the present draft. We also adapt the proofs to AlphaGo's MCTS and its descendants (e.g., AlphaZero, Leela Zero) to also show $\exp_2(\exp_2(D - O(\log D)))$ regret.

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Laurent Orseau, Remi Munos. 2024-05-07. Super-Exponential Regret for UCT, AlphaGo and Variants. https://arxiv.org/abs/2405.04407

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