Offline Policy Optimization with Posterior Sampling

Fuente: arXiv
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Main Authors: Lin, Hongqiang, Zhang, Dongxu, Sun, Yiding, Li, Mingzhe, Yang, Ning, Zhang, Haijun
Format: Preprint
Published: 2026
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author Lin, Hongqiang
Zhang, Dongxu
Sun, Yiding
Li, Mingzhe
Yang, Ning
Zhang, Haijun
author_facet Lin, Hongqiang
Zhang, Dongxu
Sun, Yiding
Li, Mingzhe
Yang, Ning
Zhang, Haijun
contents A fundamental challenge in model-based offline reinforcement learning (RL) lies in the trade-off between generalization and robustness against exploitation errors in out-of-distribution (OOD) regions. While OOD samples may capture valid underlying physical dynamics, they also introduce the risk of model exploitation. Existing methods typically address this risk through excessive pessimistic regularization, which ensures robustness but often sacrifices generalization. To overcome this limitation, we propose Posterior Sampling-based Policy Optimization (PSPO), which formulates dynamics modeling as a Bayesian inference process to derive a posterior that explicitly quantifies model fidelity. Through the integration of posterior sampling and constrained policy optimization, our method leverages dynamics-consistent OOD transitions for generalization while ensuring robustness against model exploitation. Theoretically, we formulate Q-value estimation under posterior sampling as a stochastic approximation problem and establish its convergence. We decompose policy optimization into a sequence of constrained subproblems, demonstrating that solving these subproblems guarantees monotonic improvement until convergence. Experiments on standard benchmarks validate that PSPO achieves superior performance compared to state-of-the-art baselines.
format Preprint
id arxiv_https___arxiv_org_abs_2605_07393
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Offline Policy Optimization with Posterior Sampling
Lin, Hongqiang
Zhang, Dongxu
Sun, Yiding
Li, Mingzhe
Yang, Ning
Zhang, Haijun
Artificial Intelligence
A fundamental challenge in model-based offline reinforcement learning (RL) lies in the trade-off between generalization and robustness against exploitation errors in out-of-distribution (OOD) regions. While OOD samples may capture valid underlying physical dynamics, they also introduce the risk of model exploitation. Existing methods typically address this risk through excessive pessimistic regularization, which ensures robustness but often sacrifices generalization. To overcome this limitation, we propose Posterior Sampling-based Policy Optimization (PSPO), which formulates dynamics modeling as a Bayesian inference process to derive a posterior that explicitly quantifies model fidelity. Through the integration of posterior sampling and constrained policy optimization, our method leverages dynamics-consistent OOD transitions for generalization while ensuring robustness against model exploitation. Theoretically, we formulate Q-value estimation under posterior sampling as a stochastic approximation problem and establish its convergence. We decompose policy optimization into a sequence of constrained subproblems, demonstrating that solving these subproblems guarantees monotonic improvement until convergence. Experiments on standard benchmarks validate that PSPO achieves superior performance compared to state-of-the-art baselines.
title Offline Policy Optimization with Posterior Sampling
topic Artificial Intelligence
url https://arxiv.org/abs/2605.07393