Model-free policy gradient for discrete-time mean-field control

Fuente: arXiv
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Main Authors: Meunier, Matthieu, Pham, Huyên, Reisinger, Christoph
Format: Preprint
Published: 2026
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author Meunier, Matthieu
Pham, Huyên
Reisinger, Christoph
author_facet Meunier, Matthieu
Pham, Huyên
Reisinger, Christoph
contents We study model-free policy learning for discrete-time mean-field control (MFC) problems with finite state space and compact action space. In contrast to the extensive literature on value-based methods for MFC, policy-based approaches remain largely unexplored due to the intrinsic dependence of transition kernels and rewards on the evolving population state distribution, which prevents the direct use of likelihood-ratio estimators of policy gradients from classical single-agent reinforcement learning. We introduce a novel perturbation scheme on the state-distribution flow and prove that the gradient of the resulting perturbed value function converges to the true policy gradient as the perturbation magnitude vanishes. This construction yields a fully model-free estimator based solely on simulated trajectories and an auxiliary estimate of the sensitivity of the state distribution. Building on this framework, we develop MF-REINFORCE, a model-free policy gradient algorithm for MFC, and establish explicit quantitative bounds on its bias and mean-squared error. Numerical experiments on representative mean-field control tasks demonstrate the effectiveness of the proposed approach.
format Preprint
id arxiv_https___arxiv_org_abs_2601_11217
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Model-free policy gradient for discrete-time mean-field control
Meunier, Matthieu
Pham, Huyên
Reisinger, Christoph
Optimization and Control
Machine Learning
93E20 (Primary) 60J10, 68T05, 60K35, 49N80 (Secondary)
We study model-free policy learning for discrete-time mean-field control (MFC) problems with finite state space and compact action space. In contrast to the extensive literature on value-based methods for MFC, policy-based approaches remain largely unexplored due to the intrinsic dependence of transition kernels and rewards on the evolving population state distribution, which prevents the direct use of likelihood-ratio estimators of policy gradients from classical single-agent reinforcement learning. We introduce a novel perturbation scheme on the state-distribution flow and prove that the gradient of the resulting perturbed value function converges to the true policy gradient as the perturbation magnitude vanishes. This construction yields a fully model-free estimator based solely on simulated trajectories and an auxiliary estimate of the sensitivity of the state distribution. Building on this framework, we develop MF-REINFORCE, a model-free policy gradient algorithm for MFC, and establish explicit quantitative bounds on its bias and mean-squared error. Numerical experiments on representative mean-field control tasks demonstrate the effectiveness of the proposed approach.
title Model-free policy gradient for discrete-time mean-field control
topic Optimization and Control
Machine Learning
93E20 (Primary) 60J10, 68T05, 60K35, 49N80 (Secondary)
url https://arxiv.org/abs/2601.11217