Scaf-GRPO: Scaffolded Group Relative Policy Optimization for Enhancing LLM Reasoning

Fuente: arXiv
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Main Authors: Zhang, Xichen, Wu, Sitong, Zhu, Yinghao, Tan, Haoru, Yu, Shaozuo, He, Ziyi, Jia, Jiaya
Format: Preprint
Published: 2025
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author Zhang, Xichen
Wu, Sitong
Zhu, Yinghao
Tan, Haoru
Yu, Shaozuo
He, Ziyi
Jia, Jiaya
author_facet Zhang, Xichen
Wu, Sitong
Zhu, Yinghao
Tan, Haoru
Yu, Shaozuo
He, Ziyi
Jia, Jiaya
contents Reinforcement learning from verifiable rewards has emerged as a powerful technique for enhancing the complex reasoning abilities of Large Language Models (LLMs). However, these methods are fundamentally constrained by the ''learning cliff'' phenomenon: when faced with problems far beyond their current capabilities, models consistently fail, yielding a persistent zero-reward signal. In policy optimization algorithms like GRPO, this collapses the advantage calculation to zero, rendering these difficult problems invisible to the learning gradient and stalling progress. To overcome this, we introduce Scaf-GRPO (Scaffolded Group Relative Policy Optimization), a progressive training framework that strategically provides minimal guidance only when a model's independent learning has plateaued. The framework first diagnoses learning stagnation and then intervenes by injecting tiered in-prompt hints, ranging from abstract concepts to concrete steps, enabling the model to construct a valid solution by itself. Extensive experiments on challenging mathematics benchmarks demonstrate Scaf-GRPO's effectiveness, boosting the pass@1 score of the Qwen2.5-Math-7B model on the AIME24 benchmark by a relative 44.3% over a vanilla GRPO baseline. This result demonstrates our framework provides a robust and effective methodology for unlocking a model's ability to solve problems previously beyond its reach, a critical step towards extending the frontier of autonomous reasoning in LLM.
format Preprint
id arxiv_https___arxiv_org_abs_2510_19807
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Scaf-GRPO: Scaffolded Group Relative Policy Optimization for Enhancing LLM Reasoning
Zhang, Xichen
Wu, Sitong
Zhu, Yinghao
Tan, Haoru
Yu, Shaozuo
He, Ziyi
Jia, Jiaya
Computation and Language
Artificial Intelligence
Machine Learning
Reinforcement learning from verifiable rewards has emerged as a powerful technique for enhancing the complex reasoning abilities of Large Language Models (LLMs). However, these methods are fundamentally constrained by the ''learning cliff'' phenomenon: when faced with problems far beyond their current capabilities, models consistently fail, yielding a persistent zero-reward signal. In policy optimization algorithms like GRPO, this collapses the advantage calculation to zero, rendering these difficult problems invisible to the learning gradient and stalling progress. To overcome this, we introduce Scaf-GRPO (Scaffolded Group Relative Policy Optimization), a progressive training framework that strategically provides minimal guidance only when a model's independent learning has plateaued. The framework first diagnoses learning stagnation and then intervenes by injecting tiered in-prompt hints, ranging from abstract concepts to concrete steps, enabling the model to construct a valid solution by itself. Extensive experiments on challenging mathematics benchmarks demonstrate Scaf-GRPO's effectiveness, boosting the pass@1 score of the Qwen2.5-Math-7B model on the AIME24 benchmark by a relative 44.3% over a vanilla GRPO baseline. This result demonstrates our framework provides a robust and effective methodology for unlocking a model's ability to solve problems previously beyond its reach, a critical step towards extending the frontier of autonomous reasoning in LLM.
title Scaf-GRPO: Scaffolded Group Relative Policy Optimization for Enhancing LLM Reasoning
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2510.19807