GAC: Noise-Aware Adaptive Mixing for Hybrid SFT-RL Post-Training

Yuelin Hu, Wei Liu, Zhenbo Yu, Zhengxue Cheng, Li Song


Abstract
Hybrid post-training combining supervised fine-tuning (SFT) and reinforcement learning (RL) is the standard paradigm for aligning large language models, yet fixed mixing schedules cannot adapt when the relative noise of the two signals evolves. We derive a noise-aware mixing weight by minimizing an MSE upper bound on the mixed stochastic gradient, yielding a closed-form that balances gradient noise variance and SFT–RL disagreement. Building on the token-wise reweighting of CHORD (CITATION)
Anthology ID:
2026.emnlp-main.119
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:
2763–2779
Language:
URL:
https://aclanthology.org/2026.emnlp-main.119/
DOI:
Bibkey:
Cite (ACL):
Yuelin Hu, Wei Liu, Zhenbo Yu, Zhengxue Cheng, and Li Song. 2026. GAC: Noise-Aware Adaptive Mixing for Hybrid SFT-RL Post-Training. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 2763–2779, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
GAC: Noise-Aware Adaptive Mixing for Hybrid SFT-RL Post-Training (Hu et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.119.pdf