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arXiv 2605.31455cs.LGcs.CL
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DRIFT: 解耦的轨迹采样与重要性加权微调以实现高效的多轮优化

DRIFT: Decoupled Rollouts and Importance-Weighted Fine-Tuning for Efficient Multi-Turn Optimization

The Hong Kong University of Science(香港科学与技术大学);The Chinese University of Hong Kong, Shenzhen(香港中文大学(深圳))

Jian Mu, Tianyi Lin, Chengwei Qin, Zhongxiang Dai, Yao Shu

AI总结:

针对多轮交互中在线强化学习成本高而离线监督微调存在分布偏移的问题,提出DRIFT框架,通过将KL正则化强化学习目标等价转化为重要性加权监督学习,实现高效且稳定的多轮优化。

摘要:

大型语言模型越来越多地部署在多轮交互环境中,用户或环境可以迭代地提供轻量级反馈。不幸的是,优化这种行为在实践中面临一个尖锐的困境:在线强化学习能够有效处理多轮动态,但由于每次更新时生成完整修正轨迹的成本过高而变得昂贵,而离线监督微调(SFT)虽然高效,但存在分布偏移和行为崩溃的问题。为此,我们创新性地提出了DRIFT(解耦的轨迹采样与重要性加权微调)框架,该框架实现了KL正则化强化学习目标等价于重要性加权监督学习的理论洞察。DRIFT通过从固定参考策略中采样离线交互轨迹,推导基于回报的重要性权重,并通过在所得数据集上进行加权SFT来优化策略,从而将轨迹采样与优化解耦。实验表明,DRIFT在多轮强化学习基线中达到或超越其性能,同时保持了标准监督微调的训练效率和简单性。代码可在 https://github.com/2020-qqtcg/DRIFT 获取。

英文摘要:

Large language models are increasingly deployed in multi-turn interactive settings where users or environments can iteratively provide lightweight feedback. Unfortunately, optimizing such behavior presents a sharp dilemma in practice: online reinforcement learning is able to effectively address multi-turn dynamics but is prohibitively expensive due to the cost of generating full correction trajectories at every update, whereas offline supervised fine-tuning (SFT) is efficient but suffers from distribution shift and behavioral collapse. To this end, we novelly propose DRIFT (Decoupled Rollouts and Importance-Weighted Fine-Tuning), a framework that operationalizes the theoretical insight that the KL-regularized RL objective is equivalent to importance-weighted supervised learning. DRIFT decouples rollout from optimization by sampling offline interaction trajectories from a fixed reference policy, deriving return-based importance weights, and optimizing the policy via weighted SFT on the resulting dataset. Empirically, we demonstrate that DRIFT matches or exceeds the performance of multi-turn reinforcement learning baselines while maintaining the training efficiency and simplicity of standard supervised fine-tuning. Code is available at https://github.com/2020-qqtcg/DRIFT.

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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