GRPO-VPS: Enhancing Group Relative Policy Optimization with Verifiable Process Supervision for Effective Reasoning

Fuente: arXiv
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Main Authors: Wang, Jingyi, Zhu, Lei, Weng, Tengjin, Wu, Song-Li, Tan, Haochen, Chen, Jierun, Tao, Chaofan, Bai, Haoli, Hou, Lu, Shang, Lifeng, Zhang, Xiao-Ping
Format: Preprint
Published: 2026
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author Wang, Jingyi
Zhu, Lei
Weng, Tengjin
Wu, Song-Li
Tan, Haochen
Chen, Jierun
Tao, Chaofan
Bai, Haoli
Hou, Lu
Shang, Lifeng
Zhang, Xiao-Ping
author_facet Wang, Jingyi
Zhu, Lei
Weng, Tengjin
Wu, Song-Li
Tan, Haochen
Chen, Jierun
Tao, Chaofan
Bai, Haoli
Hou, Lu
Shang, Lifeng
Zhang, Xiao-Ping
contents Reinforcement Learning with Verifiable Rewards (RLVR) has advanced the reasoning capabilities of Large Language Models (LLMs) by leveraging direct outcome verification instead of learned reward models. Building on this paradigm, Group Relative Policy Optimization (GRPO) eliminates the need for critic models but suffers from indiscriminate credit assignment for intermediate steps, which limits its ability to identify effective reasoning strategies and incurs overthinking. In this work, we introduce a model-free and verifiable process supervision via probing the model's belief in the correct answer throughout its reasoning trajectory. By segmenting the generation into discrete steps and tracking the conditional probability of the correct answer appended at each segment boundary, we efficiently compute interpretable segment-wise progress measurements to refine GRPO's trajectory-level feedback. This approach enables more targeted and sample-efficient policy updates, while avoiding the need for intermediate supervision derived from costly Monte Carlo rollouts or auxiliary models. Experiments on mathematical and general-domain benchmarks show consistent gains over GRPO across diverse models: up to 2.6-point accuracy improvements and 13.7% reasoning-length reductions on math tasks, and up to 2.4 points and 4% on general-domain tasks, demonstrating strong generalization.
format Preprint
id arxiv_https___arxiv_org_abs_2604_20659
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle GRPO-VPS: Enhancing Group Relative Policy Optimization with Verifiable Process Supervision for Effective Reasoning
Wang, Jingyi
Zhu, Lei
Weng, Tengjin
Wu, Song-Li
Tan, Haochen
Chen, Jierun
Tao, Chaofan
Bai, Haoli
Hou, Lu
Shang, Lifeng
Zhang, Xiao-Ping
Machine Learning
Artificial Intelligence
Reinforcement Learning with Verifiable Rewards (RLVR) has advanced the reasoning capabilities of Large Language Models (LLMs) by leveraging direct outcome verification instead of learned reward models. Building on this paradigm, Group Relative Policy Optimization (GRPO) eliminates the need for critic models but suffers from indiscriminate credit assignment for intermediate steps, which limits its ability to identify effective reasoning strategies and incurs overthinking. In this work, we introduce a model-free and verifiable process supervision via probing the model's belief in the correct answer throughout its reasoning trajectory. By segmenting the generation into discrete steps and tracking the conditional probability of the correct answer appended at each segment boundary, we efficiently compute interpretable segment-wise progress measurements to refine GRPO's trajectory-level feedback. This approach enables more targeted and sample-efficient policy updates, while avoiding the need for intermediate supervision derived from costly Monte Carlo rollouts or auxiliary models. Experiments on mathematical and general-domain benchmarks show consistent gains over GRPO across diverse models: up to 2.6-point accuracy improvements and 13.7% reasoning-length reductions on math tasks, and up to 2.4 points and 4% on general-domain tasks, demonstrating strong generalization.
title GRPO-VPS: Enhancing Group Relative Policy Optimization with Verifiable Process Supervision for Effective Reasoning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2604.20659