EvoRubrics: Dynamic Rubrics as Rewards via Adversarial Co-Evolution for LLM Reinforcement Learning

Hongxin Ding, Baixiang Huang, Yue Fang, Weibin Liao, Zheng Li, Jinyang Zhang, Zhijing Wu, Junfeng Zhao, Yasha Wang


Abstract
Rubric-based rewards offer interpretable and fine-grained optimization signals for reinforcement learning in open-ended tasks where verifiable answers are unavailable. However, pre-constructed rubrics remain static throughout training, creating a fundamental mismatch with the evolving policy: fixed criteria gradually lose discriminative power as the model improves, leading to reward saturation and potential hacking. Recent dynamic rubric methods partially address this but rely on external frontier models or ground-truth answers, and update rubrics only at coarse granularity. We propose EvoRubrics, a co-evolutionary RL framework where a Policy LLM and a Rubric Generator jointly improve through adversarial interaction within each training step. As the policy improves under the rubric generator’s guidance, the rubric generator adapts its criteria to remain discriminative and informative, enabling evaluation to track the policy in real time and naturally inducing an automatic curriculum. Experiments show that EvoRubrics consistently outperforms static and dynamic rubric baselines across benchmarks. The learned Rubric Generator further generalizes as a transferable reward model. Notably, even a fully self-supervised variant without any external supervision achieves meaningful gains, suggesting that co-evolution between generation and evaluation alone can provide sufficiently rich learning signals. Our code is publicly available at https://github.com/huangbaixiang100/EvoRubrics.
Anthology ID:
2026.findings-emnlp.2273
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
48660–48680
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URL:
https://aclanthology.org/2026.findings-emnlp.2273/
DOI:
Bibkey:
Cite (ACL):
Hongxin Ding, Baixiang Huang, Yue Fang, Weibin Liao, Zheng Li, Jinyang Zhang, Zhijing Wu, Junfeng Zhao, and Yasha Wang. 2026. EvoRubrics: Dynamic Rubrics as Rewards via Adversarial Co-Evolution for LLM Reinforcement Learning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 48660–48680, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
EvoRubrics: Dynamic Rubrics as Rewards via Adversarial Co-Evolution for LLM Reinforcement Learning (Ding et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2273.pdf