提出一种融合演示与探索的微调方法,提升大模型推理能力。
Blending Supervised and Reinforcement Fine-Tuning with Prefix Sampling
- 用前缀采样实现监督与强化微调的协同学习
- 在数学推理任务中性能超越单一微调及混合策略
- 对演示数据质量与数量变化具有强鲁棒性
现有大模型后训练技术主要分为监督微调(SFT)和强化微调(RFT)。SFT擅长模仿演示数据,但易导致行为克隆式泛化偏差;RFT可显著提升性能,却易学习意外行为,且对初始策略敏感。本文提出统一视角,引入Prefix-RFT,一种结合演示与探索的混合方法。以数学推理问题为测试基准,实验证明该方法简单有效:不仅优于独立的SFT与RFT,还超越并行混合策略的RFT方法。分析表明SFT与RFT具有互补性,Prefix-RFT能有效协同二者。消融实验进一步验证其对演示数据质量和数量变化的鲁棒性。
原文摘要 · Abstract (English)
Existing LLMs-post-training techniques are broadly categorized into supervised fine-tuning (SFT) and reinforcement fine-tuning (RFT). Each paradigm presents a distinct trade-off: (1) SFT excels at mimicking demonstration data, but can lead to problematic generalization as a form of behavior cloning. (2) Conversely, RFT can significantly enhance a model's performance but is prone to learning unexpected behaviors, and its performance is sensitive to the initial policy. In this paper, we propose a unified view of these methods and introduce Prefix-RFT, a hybrid approach that synergizes learning from both demonstration and exploration. Using mathematical reasoning problems as a test bed, we empirically demonstrate that Prefix-RFT is simple yet effective. Not only does it surpass the performance of standalone SFT and RFT, but it also outperforms parallel mixed-policy RFT methods. Our analysis highlights the complementary nature of SFT and RFT, validating that Prefix-RFT effectively harmonizes them. Further ablation studies confirm the method's robustness to variations in the quality and quantity of demonstration data.
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