让大模型学会处理多人复杂偏好,比传统方法更贴近真实人类判断。
Multiplayer Nash Preference Optimization
- 将对齐问题建模为多人博弈,突破单对手限制
- 在多类评测中优于现有方法,尤其在多样标注者下表现更好
- 适合需要处理复杂、非传递性偏好的实际应用
基于人类反馈的强化学习(RLHF)已成为对齐大语言模型与人类偏好的标准范式。然而,基于布拉德利-特里假设的奖励方法难以捕捉现实偏好中的非传递性和异质性。近期研究将对齐重构成双人纳什博弈,催生了纳什学习从人类反馈(NLHF)方法,如INPO、ONPO和EGPO,虽具良好理论与实证保证,但仅限于双人交互,存在单对手偏差,无法反映真实偏好结构的复杂性。本文提出多人纳什偏好优化(MNPO),首次将NLHF推广至多人场景。该框架将对齐建模为n人博弈,每个策略在对抗群体对手的同时受参考模型正则化。实验表明,MNPO继承了双人方法的均衡特性,同时实现更丰富的竞争动态与更广的偏好覆盖。全面评估显示,MNPO在指令遵循基准上持续优于现有NLHF基线,在异质标注者条件和混合策略评估中均取得更优对齐效果。结果表明,MNPO是应对复杂、非传递性人类偏好的原理性且可扩展的框架。代码已开源:https://github.com/smiles724/MNPO。
原文摘要 · Abstract (English)
Reinforcement learning from human feedback (RLHF) has emerged as the standard paradigm for aligning large language models with human preferences. However, reward-based methods grounded in the Bradley-Terry assumption struggle to capture the nontransitivity and heterogeneity of real-world preferences. To address this, recent studies have reframed alignment as a two-player Nash game, giving rise to Nash learning from human feedback (NLHF). While this perspective has inspired algorithms such as INPO, ONPO, and EGPO that offer strong theoretical and empirical guarantees, they remain fundamentally restricted to two-player interactions, introducing a single-opponent bias that fails to capture the full complexity of realistic preference structures. This work introduces Multiplayer Nash Preference Optimization (MNPO), a novel framework that generalizes NLHF to the multiplayer regime. It formulates alignment as an n-player game, where each policy competes against a population of opponents while being regularized toward a reference model. We demonstrate that MNPO inherits the equilibrium guarantees of two-player methods while enabling richer competitive dynamics and improved coverage of diverse preference structures. Comprehensive empirical evaluation shows that MNPO consistently outperforms existing NLHF baselines on instruction-following benchmarks, achieving superior alignment quality under heterogeneous annotator conditions and mixed-policy evaluation scenarios. Together, these results establish MNPO as a principled and scalable framework for aligning LLMs with complex, non-transitive human preferences. Code is available at: https://github.com/smiles724/MNPO
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