LexiSafe: Offline Safe Reinforcement Learning with Lexicographic Safety-Reward Hierarchy

Fuente: arXiv
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Main Authors: Yang, Hsin-Jung, Jiang, Zhanhong, Koirala, Prajwal, Liu, Qisai, Fleming, Cody, Sarkar, Soumik
Format: Preprint
Published: 2026
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author Yang, Hsin-Jung
Jiang, Zhanhong
Koirala, Prajwal
Liu, Qisai
Fleming, Cody
Sarkar, Soumik
author_facet Yang, Hsin-Jung
Jiang, Zhanhong
Koirala, Prajwal
Liu, Qisai
Fleming, Cody
Sarkar, Soumik
contents Offline safe reinforcement learning (RL) is increasingly important for cyber-physical systems (CPS), where safety violations during training are unacceptable and only pre-collected data are available. Existing offline safe RL methods typically balance reward-safety tradeoffs through constraint relaxation or joint optimization, but they often lack structural mechanisms to prevent safety drift. We propose LexiSafe, a lexicographic offline RL framework designed to preserve safety-aligned behavior. We first develop LexiSafe-SC, a single-cost formulation for standard offline safe RL, and derive safety-violation and performance-suboptimality bounds that together yield sample-complexity guarantees. We then extend the framework to hierarchical safety requirements with LexiSafe-MC, which supports multiple safety costs and admits its own sample-complexity analysis. Empirically, LexiSafe demonstrates reduced safety violations and improved task performance compared to constrained offline baselines. By unifying lexicographic prioritization with structural bias, LexiSafe offers a practical and theoretically grounded approach for safety-critical CPS decision-making.
format Preprint
id arxiv_https___arxiv_org_abs_2602_17312
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle LexiSafe: Offline Safe Reinforcement Learning with Lexicographic Safety-Reward Hierarchy
Yang, Hsin-Jung
Jiang, Zhanhong
Koirala, Prajwal
Liu, Qisai
Fleming, Cody
Sarkar, Soumik
Machine Learning
Systems and Control
Offline safe reinforcement learning (RL) is increasingly important for cyber-physical systems (CPS), where safety violations during training are unacceptable and only pre-collected data are available. Existing offline safe RL methods typically balance reward-safety tradeoffs through constraint relaxation or joint optimization, but they often lack structural mechanisms to prevent safety drift. We propose LexiSafe, a lexicographic offline RL framework designed to preserve safety-aligned behavior. We first develop LexiSafe-SC, a single-cost formulation for standard offline safe RL, and derive safety-violation and performance-suboptimality bounds that together yield sample-complexity guarantees. We then extend the framework to hierarchical safety requirements with LexiSafe-MC, which supports multiple safety costs and admits its own sample-complexity analysis. Empirically, LexiSafe demonstrates reduced safety violations and improved task performance compared to constrained offline baselines. By unifying lexicographic prioritization with structural bias, LexiSafe offers a practical and theoretically grounded approach for safety-critical CPS decision-making.
title LexiSafe: Offline Safe Reinforcement Learning with Lexicographic Safety-Reward Hierarchy
topic Machine Learning
Systems and Control
url https://arxiv.org/abs/2602.17312