Distill Where You Fail: Recovering Learning Signals of Negative RL-Groups from Adaptive Teacher Guidance

Zhuowen Han, Jinwei Xiao, Zhengxi Lu, Renren Jin, Zhiyuan Yao, Yuxin Liu, Hongyan Hao, Yueqing Sun, Yu Yang, Xierui Song, Xunliang Cai, Deyi Xiong


Abstract
Reinforcement learning with verifiable rewards (RLVR) has become a standard paradigm for post-training large language models (LLMs). While Group Relative Policy Optimization (GRPO) is widely adopted, it suffers from sparse reward signals and loses gradients entirely when all responses within a group receive identical rewards. On-policy distillation (OPD) offers a natural remedy by providing dense, token-level supervision from a teacher model. However, naively combining GRPO with OPD leads to degraded performance, due to three underlying causes: not all samples benefit from distillation; fitting too quickly to the teacher undermines the exploratory capacity of RL; and OPD’s advantages are asymmetric, suppressing most tokens. To address these challenges, we propose RSTG (Recovering Learning Signals via Adaptive Teacher Guidance), which applies distillation selectively and precisely where it matters most. At the sample level, OPD is restricted to negative zero-variance prompts with each sample weighted by the teacher’s confidence score. At the token level, distillation targets only tokens with high student entropy or large teacher-student divergence. We further augment training with SFT on correct trajectories generated by the teacher model, injecting positive gradient signals where RL yields none. Experiments demonstrate that RSTG substantially outperforms naive GRPO+OPD by +4.02% on math and +3.05% on code.
Anthology ID:
2026.emnlp-main.2089
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
47593–47606
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URL:
https://aclanthology.org/2026.emnlp-main.2089/
DOI:
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Cite (ACL):
Zhuowen Han, Jinwei Xiao, Zhengxi Lu, Renren Jin, Zhiyuan Yao, Yuxin Liu, Hongyan Hao, Yueqing Sun, Yu Yang, Xierui Song, Xunliang Cai, and Deyi Xiong. 2026. Distill Where You Fail: Recovering Learning Signals of Negative RL-Groups from Adaptive Teacher Guidance. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 47593–47606, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Distill Where You Fail: Recovering Learning Signals of Negative RL-Groups from Adaptive Teacher Guidance (Han et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.2089.pdf