Rank-1 Approximation of Inverse Fisher for Natural Policy Gradients in Deep Reinforcement Learning

Fuente: arXiv
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Main Authors: Huo, Yingxiao, Dash, Satya Prakash, Stoican, Radu, Kaski, Samuel, Sun, Mingfei
Format: Preprint
Published: 2026
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author Huo, Yingxiao
Dash, Satya Prakash
Stoican, Radu
Kaski, Samuel
Sun, Mingfei
author_facet Huo, Yingxiao
Dash, Satya Prakash
Stoican, Radu
Kaski, Samuel
Sun, Mingfei
contents Natural gradients have long been studied in deep reinforcement learning due to their fast convergence properties and covariant weight updates. However, computing natural gradients requires inversion of the Fisher Information Matrix (FIM) at each iteration, which is computationally prohibitive in nature. In this paper, we present an efficient and scalable natural policy optimization technique that leverages a rank-1 approximation to full inverse-FIM. We theoretically show that under certain conditions, a rank-1 approximation to inverse-FIM converges faster than policy gradients and, under some conditions, enjoys the same sample complexity as stochastic policy gradient methods. We benchmark our method on a diverse set of environments and show that it achieves superior performance to standard actor-critic and trust-region baselines.
format Preprint
id arxiv_https___arxiv_org_abs_2601_18626
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Rank-1 Approximation of Inverse Fisher for Natural Policy Gradients in Deep Reinforcement Learning
Huo, Yingxiao
Dash, Satya Prakash
Stoican, Radu
Kaski, Samuel
Sun, Mingfei
Machine Learning
Artificial Intelligence
Natural gradients have long been studied in deep reinforcement learning due to their fast convergence properties and covariant weight updates. However, computing natural gradients requires inversion of the Fisher Information Matrix (FIM) at each iteration, which is computationally prohibitive in nature. In this paper, we present an efficient and scalable natural policy optimization technique that leverages a rank-1 approximation to full inverse-FIM. We theoretically show that under certain conditions, a rank-1 approximation to inverse-FIM converges faster than policy gradients and, under some conditions, enjoys the same sample complexity as stochastic policy gradient methods. We benchmark our method on a diverse set of environments and show that it achieves superior performance to standard actor-critic and trust-region baselines.
title Rank-1 Approximation of Inverse Fisher for Natural Policy Gradients in Deep Reinforcement Learning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2601.18626