GD2PO: Group-Dynamic Reward-Decoupled Policy Optimization for Mitigating Multi-Reward RL Conflicts

Haotian Liu, Yihao Liu, Jingwei Ni, Siyuan Huang, Xinpeng Liu, Pengyu Cheng, Jiajun Song, Ruijin Ding, Junfeng Li, Zhechao Yu, Mengyu Zhou, Hongteng Xu, Xiaoxi Jiang, Guanjun Jiang


Abstract
Post-training large language models often require optimizing multiple objectives simultaneously, motivating multi-reward reinforcement learning (RL) methods that model different objectives as separate reward signals. Existing methods like Group reward-Decoupled Policy Optimization (GDPO) compute group-normalized advantages separately for each reward dimension and then aggregate them for policy updates. However, this aggregation process can cause cross-reward advantage conflict: the same rollout may have positive advantages on some reward dimensions but negative advantages on others, causing positive and negative signals to cancel each other during aggregation. To address this issue, we propose GD2PO, short for Group-Dynamic Reward-Decoupled Policy Optimization, a conflict-aware multi-reward policy optimization method. Before advantage aggregation, GD2PO uses conflict-aware criteria to identify and filter rollouts with severe reward-wise disagreement, reducing the influence of unreliable update signals. It further introduces query-level reweighting to dynamically adjust the update strength of each query according to its overall reward consensus. Experiments on tool calling and helpfulness-safety alignment show that GD2PO outperforms existing methods. Our code is available at https://github.com/Qwen-Applications/GD2PO.
Anthology ID:
2026.findings-emnlp.1070
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
Note:
Pages:
22624–22644
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URL:
https://aclanthology.org/2026.findings-emnlp.1070/
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Cite (ACL):
Haotian Liu, Yihao Liu, Jingwei Ni, Siyuan Huang, Xinpeng Liu, Pengyu Cheng, Jiajun Song, Ruijin Ding, Junfeng Li, Zhechao Yu, Mengyu Zhou, Hongteng Xu, Xiaoxi Jiang, and Guanjun Jiang. 2026. GD2PO: Group-Dynamic Reward-Decoupled Policy Optimization for Mitigating Multi-Reward RL Conflicts. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 22624–22644, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
GD2PO: Group-Dynamic Reward-Decoupled Policy Optimization for Mitigating Multi-Reward RL Conflicts (Liu et al., Findings 2026)
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https://aclanthology.org/2026.findings-emnlp.1070.pdf