Consistency-Calibrated Advantage Estimation for Label-Free Reinforcement Learning

Meng Yang, Yongle Zhao, Zhiyang Zhang, Xiaorui Jiang, Peirou Liang, Furui Chen, Yin Xie, Ziyong Feng


Abstract
Reinforcement learning from unlabeled prompts offers a promising path to improving LLM reasoning without curated supervision or verifiable rewards. However, existing label-free methods typically rely on either intrinsic self-certainty or extrinsic answer agreement, both of which can become unreliable in hard reasoning regimes: confident trajectories can be wrong, while majority answers can drift toward stable yet incorrect attractors. We propose CCAE, a verifier-free and parameter-free advantage estimator that formulates label-free GRPO as a multi-signal advantage estimation problem. CCAE decomposes the advantage into a base self-certainty term, an intrinsic evidence factor, and an extrinsic agreement factor, with their interaction adaptively calibrated by a group-level proxy for agreement reliability, without introducing any reward model, verifier, or trainable parameters. On MATH-Train, CCAE improves over the strongest unlabeled baseline by 5.0 and 4.3 points on Qwen3-4B/8B-Base, respectively, matching supervised GRPO. On the harder DAPO-14k-MATH, CCAE remains stable while prior unlabeled methods collapse, outperforming their best pre-collapse checkpoints by up to 11.1 points. Results on Natural Reasoning further suggest that CCAE remains effective beyond math-only training. Code is available at: [https://github.com/tifing/CCAE](https://github.com/tifing/CCAE).
Anthology ID:
2026.emnlp-main.2484
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:
56413–56425
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URL:
https://aclanthology.org/2026.emnlp-main.2484/
DOI:
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Cite (ACL):
Meng Yang, Yongle Zhao, Zhiyang Zhang, Xiaorui Jiang, Peirou Liang, Furui Chen, Yin Xie, and Ziyong Feng. 2026. Consistency-Calibrated Advantage Estimation for Label-Free Reinforcement Learning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 56413–56425, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Consistency-Calibrated Advantage Estimation for Label-Free Reinforcement Learning (Yang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2484.pdf