Train Long, Think Short: Curriculum Learning for Efficient Reasoning

Fuente: arXiv
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Main Authors: Hammoud, Hasan Abed Al Kader, Alhamoud, Kumail, Hammoud, Abed, Bou-Zeid, Elie, Ghassemi, Marzyeh, Ghanem, Bernard
Format: Preprint
Published: 2025
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author Hammoud, Hasan Abed Al Kader
Alhamoud, Kumail
Hammoud, Abed
Bou-Zeid, Elie
Ghassemi, Marzyeh
Ghanem, Bernard
author_facet Hammoud, Hasan Abed Al Kader
Alhamoud, Kumail
Hammoud, Abed
Bou-Zeid, Elie
Ghassemi, Marzyeh
Ghanem, Bernard
contents Recent work on enhancing the reasoning abilities of large language models (LLMs) has introduced explicit length control as a means of constraining computational cost while preserving accuracy. However, existing approaches rely on fixed-length training budgets, which do not take advantage of the natural progression from exploration to compression during learning. In this work, we propose a curriculum learning strategy for length-controlled reasoning using Group Relative Policy Optimization (GRPO). Our method starts with generous token budgets and gradually tightens them over training, encouraging models to first discover effective solution strategies and then distill them into more concise reasoning traces. We augment GRPO with a reward function that balances three signals: task correctness (via verifier feedback), length efficiency, and formatting adherence (via structural tags). Experiments on GSM8K, MATH500, SVAMP, College Math, and GSM+ demonstrate that curriculum-based training consistently outperforms fixed-budget baselines at the same final budget, achieving higher accuracy and significantly improved token efficiency. We further ablate the impact of reward weighting and decay schedule design, showing that progressive constraint serves as a powerful inductive bias for training efficient reasoning models. Our code and checkpoints are released at: https://github.com/hammoudhasan/curriculum_grpo.
format Preprint
id arxiv_https___arxiv_org_abs_2508_08940
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Train Long, Think Short: Curriculum Learning for Efficient Reasoning
Hammoud, Hasan Abed Al Kader
Alhamoud, Kumail
Hammoud, Abed
Bou-Zeid, Elie
Ghassemi, Marzyeh
Ghanem, Bernard
Computation and Language
Artificial Intelligence
Machine Learning
Recent work on enhancing the reasoning abilities of large language models (LLMs) has introduced explicit length control as a means of constraining computational cost while preserving accuracy. However, existing approaches rely on fixed-length training budgets, which do not take advantage of the natural progression from exploration to compression during learning. In this work, we propose a curriculum learning strategy for length-controlled reasoning using Group Relative Policy Optimization (GRPO). Our method starts with generous token budgets and gradually tightens them over training, encouraging models to first discover effective solution strategies and then distill them into more concise reasoning traces. We augment GRPO with a reward function that balances three signals: task correctness (via verifier feedback), length efficiency, and formatting adherence (via structural tags). Experiments on GSM8K, MATH500, SVAMP, College Math, and GSM+ demonstrate that curriculum-based training consistently outperforms fixed-budget baselines at the same final budget, achieving higher accuracy and significantly improved token efficiency. We further ablate the impact of reward weighting and decay schedule design, showing that progressive constraint serves as a powerful inductive bias for training efficient reasoning models. Our code and checkpoints are released at: https://github.com/hammoudhasan/curriculum_grpo.
title Train Long, Think Short: Curriculum Learning for Efficient Reasoning
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2508.08940