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Autori principali: Liu, Qiang, Kline, Adrienne, Wei, Ermin
Natura: Preprint
Pubblicazione: 2026
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Accesso online:https://arxiv.org/abs/2604.19024
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author Liu, Qiang
Kline, Adrienne
Wei, Ermin
author_facet Liu, Qiang
Kline, Adrienne
Wei, Ermin
contents Safe Reinforcement Learning from Human Feedback (Safe RLHF) has recently achieved empirical success in developing helpful and harmless large language models by decoupling human preferences regarding helpfulness and harmlessness. Existing approaches typically rely on fitting fixed horizon reward models from human feedback and have only been validated empirically. In this paper, we formulate safe RLHF as an infinite horizon discounted Con- strained Markov Decision Process (CMDP), since humans may interact with the model over a continuing sequence of interactions rather than within a single finite episode. We propose two Safe RLHF algorithms that do not require reward model fitting and, in contrast to prior work assuming fixed-length trajectories, support flexible trajectory lengths for training. Both algo- rithms are based on the primal-dual method and achieve global convergence guarantees with polynomial rates in terms of policy gradient iterations, trajectory sample lengths, and human preference queries. To the best of our knowledge, this is the first work to study infinite horizon discounted CMDP under human feedback and establish global, non-asymptotic convergence.
format Preprint
id arxiv_https___arxiv_org_abs_2604_19024
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Policy Gradient Primal-Dual Method for Safe Reinforcement Learning from Human Feedback
Liu, Qiang
Kline, Adrienne
Wei, Ermin
Machine Learning
Safe Reinforcement Learning from Human Feedback (Safe RLHF) has recently achieved empirical success in developing helpful and harmless large language models by decoupling human preferences regarding helpfulness and harmlessness. Existing approaches typically rely on fitting fixed horizon reward models from human feedback and have only been validated empirically. In this paper, we formulate safe RLHF as an infinite horizon discounted Con- strained Markov Decision Process (CMDP), since humans may interact with the model over a continuing sequence of interactions rather than within a single finite episode. We propose two Safe RLHF algorithms that do not require reward model fitting and, in contrast to prior work assuming fixed-length trajectories, support flexible trajectory lengths for training. Both algo- rithms are based on the primal-dual method and achieve global convergence guarantees with polynomial rates in terms of policy gradient iterations, trajectory sample lengths, and human preference queries. To the best of our knowledge, this is the first work to study infinite horizon discounted CMDP under human feedback and establish global, non-asymptotic convergence.
title Policy Gradient Primal-Dual Method for Safe Reinforcement Learning from Human Feedback
topic Machine Learning
url https://arxiv.org/abs/2604.19024