Less is More Tokens: Efficient Math Reasoning via Difficulty-Aware Chain-of-Thought Distillation

Fuente: arXiv
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Hauptverfasser: Waheed, Abdul, Mitra, Chancharik, Wang, Laurie Z., Ramanan, Deva, Raj, Bhiksha
Format: Preprint
Veröffentlicht: 2025
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author Waheed, Abdul
Mitra, Chancharik
Wang, Laurie Z.
Ramanan, Deva
Raj, Bhiksha
author_facet Waheed, Abdul
Mitra, Chancharik
Wang, Laurie Z.
Ramanan, Deva
Raj, Bhiksha
contents Chain-of-thought reasoning, while powerful, can produce unnecessarily verbose output for simpler problems. We present a framework for difficulty-aware reasoning that teaches models to dynamically adjust reasoning depth based on problem complexity. Remarkably, we show that models can be endowed with such dynamic inference pathways without any architectural modifications; we simply post-train on data that is carefully curated to include chain-of-thought traces that are proportional in length to problem difficulty. Our analysis reveals that post-training via supervised fine-tuning (SFT) primarily captures patterns like reasoning length and format, while direct preference optimization (DPO) preserves reasoning accuracy, with their combination reducing length and maintaining or improving performance. Both quantitative metrics and qualitative assessments confirm that models can learn to "think proportionally", reasoning minimally on simple problems while maintaining depth for complex ones.
format Preprint
id arxiv_https___arxiv_org_abs_2509_05226
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Less is More Tokens: Efficient Math Reasoning via Difficulty-Aware Chain-of-Thought Distillation
Waheed, Abdul
Mitra, Chancharik
Wang, Laurie Z.
Ramanan, Deva
Raj, Bhiksha
Computation and Language
Chain-of-thought reasoning, while powerful, can produce unnecessarily verbose output for simpler problems. We present a framework for difficulty-aware reasoning that teaches models to dynamically adjust reasoning depth based on problem complexity. Remarkably, we show that models can be endowed with such dynamic inference pathways without any architectural modifications; we simply post-train on data that is carefully curated to include chain-of-thought traces that are proportional in length to problem difficulty. Our analysis reveals that post-training via supervised fine-tuning (SFT) primarily captures patterns like reasoning length and format, while direct preference optimization (DPO) preserves reasoning accuracy, with their combination reducing length and maintaining or improving performance. Both quantitative metrics and qualitative assessments confirm that models can learn to "think proportionally", reasoning minimally on simple problems while maintaining depth for complex ones.
title Less is More Tokens: Efficient Math Reasoning via Difficulty-Aware Chain-of-Thought Distillation
topic Computation and Language
url https://arxiv.org/abs/2509.05226