arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2605.08037cs.LGcs.AI

超越成对:你的语言模型其实是在优化一个偏好图

Beyond Pairs: Your Language Model is Secretly Optimizing a Preference Graph

Amazon(亚马逊)

Ning Liu, Chuanneng Sun, Kristina Klinkner, Shervin Malmasi

AI总结:

本文提出GraphDPO,通过构建偏好图结构优化语言模型,解决传统成对优化在处理多轮次数据时的局限性,提升模型在推理和编程任务中的性能。

摘要:

直接偏好优化(DPO)通过成对偏好比较对语言模型进行对齐,提供了一种简单有效的替代强化学习(RL)从人类反馈的方法。然而,在许多实际场景中,训练数据包含每个提示的多个轮次,导致丰富的偏好结构,而传统的成对DPO无法利用这些信息。本文提出图直接偏好优化(GraphDPO),一种基于由轮次排名诱导的有向无环偏好图的DPO扩展方法。GraphDPO将支配关系编码为边,并优化一种基于Plackett-Luce启发式的图结构目标函数,通过图邻域聚合监督,强制传递性并恢复标准DPO为特殊情况。为处理离散或稀疏信号,引入等价类构造,相同偏好的响应形成图层,层内边贡献零损失,防止虚假梯度。尽管利用完整图结构,GraphDPO通过高效的log-sum-exp聚合保持线性每提示复杂度。进一步引入可选的真实解锚定,通过插入已验证的解决方案作为主导节点,并应用退火调度,稳定早期训练同时逐渐放松 oracle 监督。在推理和编程合成任务中的实验显示,GraphDPO表现优于传统方法,表明图结构偏好建模是可扩展且稳健的替代方案。

英文摘要:

Direct Preference Optimization (DPO) aligns language models using pairwise preference comparisons, offering a simple and effective alternative to Reinforcement Learning (RL) from human feedback. However, in many practical settings, training data consists of multiple rollouts per prompt, inducing rich preference structure that pairwise DPO fails to exploit. Collapsing such data into independent pairs discards transitivity, introduces redundant or conflicting supervision, and can lead to unstable optimization. We propose Graph Direct Preference Optimization (GraphDPO), a structured generalization of DPO that operates over directed acyclic preference graphs induced by rollout rankings. GraphDPO encodes dominance relations as edges and optimizes a graph-structured Plackett--Luce-inspired objective that aggregates supervision over dominated neighborhoods, propagating the transitive structure of the input preferences while recovering standard DPO as a special case. GraphDPO naturally handles tied and incomparable responses through an equivalence-class construction: responses with identical preference signals form graph layers, incomparable responses share a layer without an edge, and absent edges contribute zero loss, preventing the spurious gradients that strict total-order objectives incur. Under this layered construction, GraphDPO maintains linear per-prompt complexity via efficient log-sum-exp aggregation. We further incorporate optional ground-truth anchoring by inserting verified solutions as dominant nodes and applying an annealed schedule that stabilizes early training while gradually relaxing oracle supervision. Experiments on reasoning and program synthesis tasks demonstrate superior performance, suggesting that graph-structured preference modeling is a scalable and robust alternative to pairwise and listwise alignment objectives.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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