提出一种新框架,让大模型对齐更抗噪声标签干扰。
RE-PO: Robust Enhanced Policy Optimization as a General Framework for LLM Alignment
- 用期望最大化法推断每条反馈的可信度,动态调整训练权重。
- 在多个主流对齐方法上提升性能,最高使评测胜率提高7.0%。
- 可通用改造现有对齐算法,适合高噪声数据场景使用。
标准的人类偏好对齐方法(如基于人类反馈的强化学习)是使大语言模型与人类价值观对齐的核心手段。然而,这些方法通常假设偏好数据干净且标签可靠。实际中,大规模偏好数据集因标注者错误、指令不一致、专业水平差异甚至恶意或敷衍反馈而存在大量噪声。这种标注与真实偏好之间的偏差会误导训练并降低模型性能。为此,我们提出鲁棒增强策略优化(RE-PO),通过期望最大化过程推断每条标签的后验正确性,并自适应地重新加权训练损失中的数据点以缓解标签噪声。进一步地,我们建立了任意偏好损失与其潜在概率模型之间的理论联系,系统性地将现有对齐算法转化为鲁棒版本,使RE-PO从单一方法升维为通用的鲁棒偏好对齐框架。理论上,当模型完全校准时,RE-PO能恢复数据集的真实噪声水平。实证上,我们证明RE-PO在四种前沿对齐方法(DPO、IPO、SimPO、CPO)上均持续提升性能;应用于Mistral和Llama 3模型时,其增强版本在AlpacaEval 2评测中胜率最高比基线提升7.0%。
原文摘要 · Abstract (English)
Standard human preference-based alignment methods, such as Reinforcement Learning from Human Feedback (RLHF), are a cornerstone for aligning large language models (LLMs) with human values. However, these methods typically assume that preference data is clean and that all labels are equally reliable. In practice, large-scale preference datasets contain substantial noise due to annotator mistakes, inconsistent instructions, varying expertise, and even adversarial or low-effort feedback. This mismatch between recorded labels and ground-truth preferences can misguide training and degrade model performance. To address this issue, we introduce Robust Enhanced Policy Optimization (RE-PO), which uses an expectation-maximization procedure to infer the posterior correctness of each label and then adaptively reweight data points in the training loss to mitigate label noise. We further generalize this idea by establishing a theoretical link between arbitrary preference losses and their underlying probabilistic models, enabling a systematic transformation of existing alignment algorithms into robust counterparts and elevating RE-PO from a single method to a general framework for robust preference alignment. Theoretically, we prove that, under a perfectly calibrated model, RE-PO recovers the true noise level of the dataset. Empirically, we show that RE-PO consistently improves four state-of-the-art alignment methods (DPO, IPO, SimPO, and CPO); when applied to Mistral and Llama 3 models, the RE-PO-enhanced variants increase AlpacaEval 2 win rates by up to 7.0 percent over their respective baselines.
Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。