Thinking Machines Lab 发布 On-Policy Distillation 研究:用稠密教师监督替代 RL 后训练
Thinking Machines Lab 发布 On-Policy Distillation 研究,提出从学生模型采样轨迹、由教师模型逐 token 打分并最小化 reverse KL 的后训练方法,结合了 on-policy 训练与稠密奖励信号。在数学推理实验中,Qwen3-8B-Base 经 400k 提示 SFT 后在 AIME'24 得 60%,再用 on-policy distillation 约 150 步达到 70%;作者称在已有 SFT 数据集时计算成本约为 off-policy 的 1/9,若计入教师采样成本则约 1/30,与 RL 相比训练步数快 7-10 倍。该方法还被用于内部文档助手场景,在 70-30 文档与对话数据混合微调后恢复 IF-eval 表现且不损失知识,实现代码见 Tinker cookbook。
t learning only trains small subnetworks of the original model,Reinforcement Learning Finetunes Small Subnetworks in Large Language Models (Mukherjee et al, 2025) and thus can be fragile when the network is further trained on a large amount of data. We study the extent to which it happens, and how the desired behavior can be recovered. In order to reduce such catastrophic forgetting, a common approach in mid-training is to mix in “background data” from the original model’s pretraining distributi
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