TinyV: Reducing False Negatives in Verification Improves RL for LLM Reasoning

Fuente: arXiv
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Autori principali: Xu, Zhangchen, Li, Yuetai, Jiang, Fengqing, Ramasubramanian, Bhaskar, Niu, Luyao, Lin, Bill Yuchen, Poovendran, Radha
Natura: Preprint
Pubblicazione: 2025
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author Xu, Zhangchen
Li, Yuetai
Jiang, Fengqing
Ramasubramanian, Bhaskar
Niu, Luyao
Lin, Bill Yuchen
Poovendran, Radha
author_facet Xu, Zhangchen
Li, Yuetai
Jiang, Fengqing
Ramasubramanian, Bhaskar
Niu, Luyao
Lin, Bill Yuchen
Poovendran, Radha
contents Reinforcement Learning (RL) has become a powerful tool for enhancing the reasoning abilities of large language models (LLMs) by optimizing their policies with reward signals. Yet, RL's success relies on the reliability of rewards, which are provided by verifiers. In this paper, we expose and analyze a widespread problem--false negatives--where verifiers wrongly reject correct model outputs. Our in-depth study of the Big-Math-RL-Verified dataset reveals that over 38% of model-generated responses suffer from false negatives, where the verifier fails to recognize correct answers. We show, both empirically and theoretically, that these false negatives severely impair RL training by depriving the model of informative gradient signals and slowing convergence. To mitigate this, we propose tinyV, a lightweight LLM-based verifier that augments existing rule-based methods, which dynamically identifies potential false negatives and recovers valid responses to produce more accurate reward estimates. Across multiple math-reasoning benchmarks, integrating TinyV boosts pass rates by up to 10% and accelerates convergence relative to the baseline. Our findings highlight the critical importance of addressing verifier false negatives and offer a practical approach to improve RL-based fine-tuning of LLMs. Our code is available at https://github.com/uw-nsl/TinyV.
format Preprint
id arxiv_https___arxiv_org_abs_2505_14625
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle TinyV: Reducing False Negatives in Verification Improves RL for LLM Reasoning
Xu, Zhangchen
Li, Yuetai
Jiang, Fengqing
Ramasubramanian, Bhaskar
Niu, Luyao
Lin, Bill Yuchen
Poovendran, Radha
Machine Learning
Artificial Intelligence
Computation and Language
Reinforcement Learning (RL) has become a powerful tool for enhancing the reasoning abilities of large language models (LLMs) by optimizing their policies with reward signals. Yet, RL's success relies on the reliability of rewards, which are provided by verifiers. In this paper, we expose and analyze a widespread problem--false negatives--where verifiers wrongly reject correct model outputs. Our in-depth study of the Big-Math-RL-Verified dataset reveals that over 38% of model-generated responses suffer from false negatives, where the verifier fails to recognize correct answers. We show, both empirically and theoretically, that these false negatives severely impair RL training by depriving the model of informative gradient signals and slowing convergence. To mitigate this, we propose tinyV, a lightweight LLM-based verifier that augments existing rule-based methods, which dynamically identifies potential false negatives and recovers valid responses to produce more accurate reward estimates. Across multiple math-reasoning benchmarks, integrating TinyV boosts pass rates by up to 10% and accelerates convergence relative to the baseline. Our findings highlight the critical importance of addressing verifier false negatives and offer a practical approach to improve RL-based fine-tuning of LLMs. Our code is available at https://github.com/uw-nsl/TinyV.
title TinyV: Reducing False Negatives in Verification Improves RL for LLM Reasoning
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2505.14625