Mitigating False Credit Propagation: Probabilistic Graphical Reward Aggregation for Rubric-Based Reinforcement Learning

Can Lv, Mingju Chen, Heng Chang, Shiji Zhou


Abstract
Rubric-based rewards are increasingly used for open-ended language model post-training, but criterion-level scores are commonly aggregated as independent utilities. This flat scalarization ignores semantic dependencies among criteria, allowing downstream credit or penalties to be counted even when the conditions that license them are absent. We call this structural failure False Credit Propagation (FCP).

We propose GEAR (Graphical Event Aggregation for Rubric rewards), a dependency-aware aggregation framework for rubric rewards. GEAR represents rubric criteria as latent events in a typed dependency graph, uses monotone retention factors to infer dependency-adjusted criterion marginals, and computes a normalized expected-utility reward.

This preserves compatibility with standard rubric-based reinforcement learning while adding only linear-time aggregation over criteria and edges. Experiments on HealthBench, WritingBench, and PLawBench with two policy backbones show that GEAR consistently improves over flat aggregation and hard gating, both in controlled aggregation-only settings and as a plug-in module for existing rubric-guided RL pipelines.

FCP diagnostics further show that GEAR substantially reduces invalid downstream utility while avoiding the over-suppression of deterministic gating.
Anthology ID:
2026.emnlp-main.1933
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
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Pages:
43980–44003
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URL:
https://aclanthology.org/2026.emnlp-main.1933/
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Cite (ACL):
Can Lv, Mingju Chen, Heng Chang, and Shiji Zhou. 2026. Mitigating False Credit Propagation: Probabilistic Graphical Reward Aggregation for Rubric-Based Reinforcement Learning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 43980–44003, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Mitigating False Credit Propagation: Probabilistic Graphical Reward Aggregation for Rubric-Based Reinforcement Learning (Lv et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.1933.pdf