Federated Temporal Difference Learning with Linear Function Approximation under Environmental Heterogeneity

Fuente: arXiv
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Autores principales: Wang, Han, Mitra, Aritra, Hassani, Hamed, Pappas, George J., Anderson, James
Formato: Preprint
Publicado: 2023
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author Wang, Han
Mitra, Aritra
Hassani, Hamed
Pappas, George J.
Anderson, James
author_facet Wang, Han
Mitra, Aritra
Hassani, Hamed
Pappas, George J.
Anderson, James
contents We initiate the study of federated reinforcement learning under environmental heterogeneity by considering a policy evaluation problem. Our setup involves $N$ agents interacting with environments that share the same state and action space but differ in their reward functions and state transition kernels. Assuming agents can communicate via a central server, we ask: Does exchanging information expedite the process of evaluating a common policy? To answer this question, we provide the first comprehensive finite-time analysis of a federated temporal difference (TD) learning algorithm with linear function approximation, while accounting for Markovian sampling, heterogeneity in the agents' environments, and multiple local updates to save communication. Our analysis crucially relies on several novel ingredients: (i) deriving perturbation bounds on TD fixed points as a function of the heterogeneity in the agents' underlying Markov decision processes (MDPs); (ii) introducing a virtual MDP to closely approximate the dynamics of the federated TD algorithm; and (iii) using the virtual MDP to make explicit connections to federated optimization. Putting these pieces together, we rigorously prove that in a low-heterogeneity regime, exchanging model estimates leads to linear convergence speedups in the number of agents.
format Preprint
id arxiv_https___arxiv_org_abs_2302_02212
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Federated Temporal Difference Learning with Linear Function Approximation under Environmental Heterogeneity
Wang, Han
Mitra, Aritra
Hassani, Hamed
Pappas, George J.
Anderson, James
Machine Learning
Optimization and Control
We initiate the study of federated reinforcement learning under environmental heterogeneity by considering a policy evaluation problem. Our setup involves $N$ agents interacting with environments that share the same state and action space but differ in their reward functions and state transition kernels. Assuming agents can communicate via a central server, we ask: Does exchanging information expedite the process of evaluating a common policy? To answer this question, we provide the first comprehensive finite-time analysis of a federated temporal difference (TD) learning algorithm with linear function approximation, while accounting for Markovian sampling, heterogeneity in the agents' environments, and multiple local updates to save communication. Our analysis crucially relies on several novel ingredients: (i) deriving perturbation bounds on TD fixed points as a function of the heterogeneity in the agents' underlying Markov decision processes (MDPs); (ii) introducing a virtual MDP to closely approximate the dynamics of the federated TD algorithm; and (iii) using the virtual MDP to make explicit connections to federated optimization. Putting these pieces together, we rigorously prove that in a low-heterogeneity regime, exchanging model estimates leads to linear convergence speedups in the number of agents.
title Federated Temporal Difference Learning with Linear Function Approximation under Environmental Heterogeneity
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2302.02212