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Main Authors: Sun, Lin, Liu, Chuang, Ma, Xiaofeng, Yang, Tao, Lu, Weijia, Wu, Ning
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2506.03570
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author Sun, Lin
Liu, Chuang
Ma, Xiaofeng
Yang, Tao
Lu, Weijia
Wu, Ning
author_facet Sun, Lin
Liu, Chuang
Ma, Xiaofeng
Yang, Tao
Lu, Weijia
Wu, Ning
contents Recent advancements in Large Language Models (LLMs) have demonstrated that Process Reward Models (PRMs) play a crucial role in enhancing model performance. However, training PRMs typically requires step-level labels, either manually annotated or automatically generated, which can be costly and difficult to obtain at scale. To address this challenge, we introduce FreePRM, a weakly supervised framework for training PRMs without access to ground-truth step-level labels. FreePRM first generates pseudo step-level labels based on the correctness of final outcome, and then employs Buffer Probability to eliminate impact of noise inherent in pseudo labeling. Experimental results show that FreePRM achieves an average F1 score of 53.0% on ProcessBench, outperforming fully supervised PRM trained on Math-Shepherd by +24.1%. Compared to other open-source PRMs, FreePRM outperforms upon RLHFlow-PRM-Mistral-8B (28.4%) by +24.6%, EurusPRM (31.3%) by +21.7%, and Skywork-PRM-7B (42.1%) by +10.9%. This work introduces a new paradigm in PRM training, significantly reducing reliance on costly step-level annotations while maintaining strong performance.
format Preprint
id arxiv_https___arxiv_org_abs_2506_03570
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle FreePRM: Training Process Reward Models Without Ground Truth Process Labels
Sun, Lin
Liu, Chuang
Ma, Xiaofeng
Yang, Tao
Lu, Weijia
Wu, Ning
Computation and Language
Recent advancements in Large Language Models (LLMs) have demonstrated that Process Reward Models (PRMs) play a crucial role in enhancing model performance. However, training PRMs typically requires step-level labels, either manually annotated or automatically generated, which can be costly and difficult to obtain at scale. To address this challenge, we introduce FreePRM, a weakly supervised framework for training PRMs without access to ground-truth step-level labels. FreePRM first generates pseudo step-level labels based on the correctness of final outcome, and then employs Buffer Probability to eliminate impact of noise inherent in pseudo labeling. Experimental results show that FreePRM achieves an average F1 score of 53.0% on ProcessBench, outperforming fully supervised PRM trained on Math-Shepherd by +24.1%. Compared to other open-source PRMs, FreePRM outperforms upon RLHFlow-PRM-Mistral-8B (28.4%) by +24.6%, EurusPRM (31.3%) by +21.7%, and Skywork-PRM-7B (42.1%) by +10.9%. This work introduces a new paradigm in PRM training, significantly reducing reliance on costly step-level annotations while maintaining strong performance.
title FreePRM: Training Process Reward Models Without Ground Truth Process Labels
topic Computation and Language
url https://arxiv.org/abs/2506.03570