Robust Regularized Policy Iteration under Transition Uncertainty

Fuente: arXiv
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Auteurs principaux: Lin, Hongqiang, Fu, Zhenghui, Tang, Weihao, Wang, Pengfei, Sun, Yiding, Huang, Qixian, Zhang, Dongxu
Format: Preprint
Publié: 2026
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author Lin, Hongqiang
Fu, Zhenghui
Tang, Weihao
Wang, Pengfei
Sun, Yiding
Huang, Qixian
Zhang, Dongxu
author_facet Lin, Hongqiang
Fu, Zhenghui
Tang, Weihao
Wang, Pengfei
Sun, Yiding
Huang, Qixian
Zhang, Dongxu
contents Offline reinforcement learning (RL) enables data-efficient and safe policy learning without online exploration, but its performance often degrades under distribution shift. The learned policy may visit out-of-distribution state-action pairs where value estimates and learned dynamics are unreliable. To address policy-induced extrapolation and transition uncertainty in a unified framework, we formulate offline RL as robust policy optimization, treating the transition kernel as a decision variable within an uncertainty set and optimizing the policy against the worst-case dynamics. We propose Robust Regularized Policy Iteration (RRPI), which replaces the intractable max-min bilevel objective with a tractable KL-regularized surrogate and derives an efficient policy iteration procedure based on a robust regularized Bellman operator. We provide theoretical guarantees by showing that the proposed operator is a $γ$-contraction and that iteratively updating the surrogate yields monotonic improvement of the original robust objective with convergence. Experiments on D4RL benchmarks demonstrate that RRPI achieves strong average performance, outperforming recent baselines including percentile-based methods on the majority of environments while remaining competitive on the rest. Moreover, RRPI exhibits robust performance by aligning lower $Q$-values with high epistemic uncertainty, which prevents the policy from executing unreliable out-of-distribution actions.
format Preprint
id arxiv_https___arxiv_org_abs_2603_09344
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Robust Regularized Policy Iteration under Transition Uncertainty
Lin, Hongqiang
Fu, Zhenghui
Tang, Weihao
Wang, Pengfei
Sun, Yiding
Huang, Qixian
Zhang, Dongxu
Artificial Intelligence
Machine Learning
Offline reinforcement learning (RL) enables data-efficient and safe policy learning without online exploration, but its performance often degrades under distribution shift. The learned policy may visit out-of-distribution state-action pairs where value estimates and learned dynamics are unreliable. To address policy-induced extrapolation and transition uncertainty in a unified framework, we formulate offline RL as robust policy optimization, treating the transition kernel as a decision variable within an uncertainty set and optimizing the policy against the worst-case dynamics. We propose Robust Regularized Policy Iteration (RRPI), which replaces the intractable max-min bilevel objective with a tractable KL-regularized surrogate and derives an efficient policy iteration procedure based on a robust regularized Bellman operator. We provide theoretical guarantees by showing that the proposed operator is a $γ$-contraction and that iteratively updating the surrogate yields monotonic improvement of the original robust objective with convergence. Experiments on D4RL benchmarks demonstrate that RRPI achieves strong average performance, outperforming recent baselines including percentile-based methods on the majority of environments while remaining competitive on the rest. Moreover, RRPI exhibits robust performance by aligning lower $Q$-values with high epistemic uncertainty, which prevents the policy from executing unreliable out-of-distribution actions.
title Robust Regularized Policy Iteration under Transition Uncertainty
topic Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2603.09344