Global Convergence of Natural Policy Gradient with Hessian-aided Momentum Variance Reduction

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Hauptverfasser: Feng, Jie, Wei, Ke, Chen, Jinchi
Format: Preprint
Veröffentlicht: 2024
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author Feng, Jie
Wei, Ke
Chen, Jinchi
author_facet Feng, Jie
Wei, Ke
Chen, Jinchi
contents Natural policy gradient (NPG) and its variants are widely-used policy search methods in reinforcement learning. Inspired by prior work, a new NPG variant coined NPG-HM is developed in this paper, which utilizes the Hessian-aided momentum technique for variance reduction, while the sub-problem is solved via the stochastic gradient descent method. It is shown that NPG-HM can achieve the global last iterate $ε$-optimality with a sample complexity of $\mathcal{O}(ε^{-2})$, which is the best known result for natural policy gradient type methods under the generic Fisher non-degenerate policy parameterizations. The convergence analysis is built upon a relaxed weak gradient dominance property tailored for NPG under the compatible function approximation framework, as well as a neat way to decompose the error when handling the sub-problem. Moreover, numerical experiments on Mujoco-based environments demonstrate the superior performance of NPG-HM over other state-of-the-art policy gradient methods.
format Preprint
id arxiv_https___arxiv_org_abs_2401_01084
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Global Convergence of Natural Policy Gradient with Hessian-aided Momentum Variance Reduction
Feng, Jie
Wei, Ke
Chen, Jinchi
Machine Learning
Optimization and Control
Natural policy gradient (NPG) and its variants are widely-used policy search methods in reinforcement learning. Inspired by prior work, a new NPG variant coined NPG-HM is developed in this paper, which utilizes the Hessian-aided momentum technique for variance reduction, while the sub-problem is solved via the stochastic gradient descent method. It is shown that NPG-HM can achieve the global last iterate $ε$-optimality with a sample complexity of $\mathcal{O}(ε^{-2})$, which is the best known result for natural policy gradient type methods under the generic Fisher non-degenerate policy parameterizations. The convergence analysis is built upon a relaxed weak gradient dominance property tailored for NPG under the compatible function approximation framework, as well as a neat way to decompose the error when handling the sub-problem. Moreover, numerical experiments on Mujoco-based environments demonstrate the superior performance of NPG-HM over other state-of-the-art policy gradient methods.
title Global Convergence of Natural Policy Gradient with Hessian-aided Momentum Variance Reduction
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2401.01084