让大模型同时满足多种冲突需求,通过自适应梯度优化实现更好对齐。
Gradient-Adaptive Policy Optimization: Towards Multi-Objective Alignment of Large Language Models
- 用多梯度下降动态调整各目标梯度,平衡不同人类偏好间的冲突。
- 在Mistral-7B上表现优于现有方法,帮助性与安全性双提升。
- 适合需要多目标调优的场景,如内容生成、对话系统等应用。
基于人类反馈的强化学习(RLHF)已成为对齐大语言模型(LLMs)与人类偏好的有力手段。然而,在存在多种相互冲突的人类偏好时,有效对齐仍具挑战。为此,我们将人类价值观对齐问题建模为多目标优化问题,旨在最大化一组可能冲突的目标。我们提出梯度自适应策略优化(GAPO),一种新型微调范式,采用多梯度下降法对齐LLMs与多样化的偏好分布。GAPO 自适应地缩放每个目标的梯度,以确定在各目标间最优权衡的更新方向。此外,我们引入P-GAPO,融合用户在不同目标上的偏好,获得更贴近用户具体需求的帕累托解。理论分析表明,GAPO 收敛至多目标帕累托最优解。在 Mistral-7B 上的实验结果表明,GAPO 优于当前最先进的方法,在帮助性和无害性方面均取得更优性能。
原文摘要 · Abstract (English)
Reinforcement Learning from Human Feedback (RLHF) has emerged as a powerful technique for aligning large language models (LLMs) with human preferences. However, effectively aligning LLMs with diverse human preferences remains a significant challenge, particularly when they are conflict. To address this issue, we frame human value alignment as a multi-objective optimization problem, aiming to maximize a set of potentially conflicting objectives. We introduce Gradient-Adaptive Policy Optimization (GAPO), a novel fine-tuning paradigm that employs multiple-gradient descent to align LLMs with diverse preference distributions. GAPO adaptively rescales the gradients for each objective to determine an update direction that optimally balances the trade-offs between objectives. Additionally, we introduce P-GAPO, which incorporates user preferences across different objectives and achieves Pareto solutions that better align with the user's specific needs. Our theoretical analysis demonstrates that GAPO converges towards a Pareto optimal solution for multiple objectives. Empirical results on Mistral-7B show that GAPO outperforms current state-of-the-art methods, achieving superior performance in both helpfulness and harmlessness.
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