Related papers: Minimax-Optimal Multi-Agent RL in Zero-Sum Markov Games With a Generative Model

Minimax-Optimal Multi-Agent RL in Zero-Sum Markov Games With a Generative Model

URL: http://arxiv.org/abs/2208.10458v1
Date: Mon, 22 Aug 2022 17:24:55 GMT
Title: Minimax-Optimal Multi-Agent RL in Zero-Sum Markov Games With a Generative Model
Authors: Gen Li, Yuejie Chi, Yuting Wei, Yuxin Chen
Abstract summary: Two-player zero-sum Markov games are arguably the most basic setting in multi-agent reinforcement learning. We develop a learning algorithm that learns an $varepsilon$-approximate Markov NE policy using $$ widetildeObigg. We derive a refined regret bound for FTRL that makes explicit the role of variance-type quantities.
Score: 50.38446482252857
License: http://creativecommons.org/licenses/by/4.0/
Abstract: This paper is concerned with two-player zero-sum Markov games -- arguably the most basic setting in multi-agent reinforcement learning -- with the goal of learning a Nash equilibrium (NE) sample-optimally. All prior results suffer from at least one of the two obstacles: the curse of multiple agents and the barrier of long horizon, regardless of the sampling protocol in use. We take a step towards settling this problem, assuming access to a flexible sampling mechanism: the generative model. Focusing on non-stationary finite-horizon Markov games, we develop a learning algorithm $\mathsf{Nash}\text{-}\mathsf{Q}\text{-}\mathsf{FTRL}$ and an adaptive sampling scheme that leverage the optimism principle in adversarial learning (particularly the Follow-the-Regularized-Leader (FTRL) method), with a delicate design of bonus terms that ensure certain decomposability under the FTRL dynamics. Our algorithm learns an $\varepsilon$-approximate Markov NE policy using $$ \widetilde{O}\bigg( \frac{H^4 S(A+B)}{\varepsilon^2} \bigg) $$ samples, where $S$ is the number of states, $H$ is the horizon, and $A$ (resp.~$B$) denotes the number of actions for the max-player (resp.~min-player). This is nearly un-improvable in a minimax sense. Along the way, we derive a refined regret bound for FTRL that makes explicit the role of variance-type quantities, which might be of independent interest.