Silence the Judge: Reinforcement Learning with Self-Verifier via Latent Geometric Clustering

Nonghai Zhang, Weitao Ma, Zhanyu Ma, Jun Xu, Jiuchong Gao, Jinghua Hao, Renqing He, Jingwen Xu


Abstract
Group Relative Policy Optimization (GRPO) significantly enhances the reasoning performance of Large Language Models (LLMs). However, this success heavily relies on expensive external verifiers or human rules. Such dependency not only leads to significant computational costs and training latency, but also yields sparse rewards that hinder optimization efficiency. To address these challenges, we propose Latent-GRPO, a framework that derives intrinsic rewards directly from latent space geometry. Crucially, our empirical analysis reveals a compelling geometric property: terminal token representations of correct reasoning trajectories form dense clusters with high intra-class similarity, whereas incorrect trajectories remain scattered as outliers. In light of this discovery, we introduce the Iterative Robust Centroid Estimation (IRCE) algorithm, which generates dense, continuous rewards by mitigating magnitude fluctuations via spherical projection and estimating a robust “truth centroid” through iterative aggregation. Experimental results on multiple datasets show that our method maintains model performance while achieving a training speedup of over 2x compared to baselines. Furthermore, extensive results demonstrate strong generalization ability and robustness.
Anthology ID:
2026.emnlp-main.2569
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:
58355–58373
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2569/
DOI:
Bibkey:
Cite (ACL):
Nonghai Zhang, Weitao Ma, Zhanyu Ma, Jun Xu, Jiuchong Gao, Jinghua Hao, Renqing He, and Jingwen Xu. 2026. Silence the Judge: Reinforcement Learning with Self-Verifier via Latent Geometric Clustering. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 58355–58373, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Silence the Judge: Reinforcement Learning with Self-Verifier via Latent Geometric Clustering (Zhang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2569.pdf