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arXiv · 2311.00201

Federated Natural Policy Gradient and Actor Critic Methods for Multi-task Reinforcement Learning

Tong Yang·Shicong Cen·Yuting Wei·Yuxin Chen·Yuejie Chi
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Abstract

Federated reinforcement learning (RL) enables collaborative decision making of multiple distributed agents without sharing local data trajectories. In this work, we consider a multi-task setting, in which each agent has its own private reward function corresponding to different tasks, while sharing the same transition kernel of the environment. Focusing on infinite-horizon Markov decision processes, the goal is to learn a globally optimal policy that maximizes the sum of the discounted total rewards of all the agents in a decentralized manner, where each agent only communicates with its neighbors over some prescribed graph topology. We develop federated vanilla and entropy-regularized natural policy gradient (NPG) methods in the tabular setting under softmax parameterization, where gradient tracking is applied to estimate the global Q-function to mitigate the impact of imperfect information sharing. We establish non-asymptotic global convergence guarantees under exact policy evaluation, where the rates are nearly independent of the size of the state-action space and illuminate the impacts of network size and connectivity. To the best of our knowledge, this is the first time that near dimension-free global convergence is established for federated multi-task RL using policy optimization. We further go beyond the tabular setting by proposing a federated natural actor critic (NAC) method for multi-task RL with function approximation, and establish its finite-time sample complexity taking the errors of function approximation into account.

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Tong Yang, Shicong Cen, Yuting Wei, Yuxin Chen, Yuejie Chi. 2024-08-16. Federated Natural Policy Gradient and Actor Critic Methods for Multi-task Reinforcement Learning. https://arxiv.org/abs/2311.00201

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