Do NOT Think That Much for 2+3=? On the Overthinking of o1-Like LLMs
Written for the Research library (claude-opus-5-5) from the paper text, in our own words: the license "arXiv — non-exclusive license to distribute" does not allow redistributing the text itself. Original — arxiv.org/pdf/2412.21187
Summary
Reasoning models in the o1 family get better accuracy by writing very long chains of thought. This paper argues that much of that extra test-time compute is wasted. The authors call the waste "overthinking": after a model already has the right answer to a trivial question, it keeps producing new solution attempts. They studied QwQ-32B-Preview and DeepSeek-R1 on ASDIV, GSM8K and MATH500. The extra rounds rarely change the answer and seldom try a new approach. They also happen more often on easy problems than on hard ones. The authors add two efficiency metrics to plain accuracy. One looks at outcomes (how many tokens were needed to reach the correct answer) and the other at the process (how varied the reasoning is). To reduce overthinking they use self-training. They take the model's own sampled outputs and cut out redundant solutions, for example keeping everything up to the first correct solution plus one reflection step. They then train on these shorter outputs with SFT or preference optimization. This makes reasoning much shorter while keeping accuracy, which matters for anyone running reasoning LLMs with limited budget or latency.
Key points
- For the question "2 plus 3", o1-like models used about 1,953% more tokens than conventional LLMs. In one example, QwQ-32B-Preview wrote 13 separate solutions. Solutions were split out of responses with Llama-3.3-70B.
- The first solution round was already correct in more than 92% of correctly answered cases. On ASDIV, for instance, it made up only about 38.7% of QwQ's output.
- Among the training methods, SimPO beat SFT and the other preference-optimization variants, cutting tokens by 22.3% on MATH500. "FCS+Reflection" was the best way to simplify responses, beating plain FCS by 1.4 accuracy points on MATH500.
- The combined approach cut QwQ-32B-Preview's output on MATH500 by 48.6% with no loss of accuracy. Accuracy held on the harder GPQA and AIME sets and improved on ASDIV and GSM8K.
Cited by
- L1: Controlling How Long A Reasoning Model Thinks With Reinforcement Learning
- Towards Reasoning Era: A Survey of Long Chain-of-Thought for Reasoning Large Language Models
- OpenThoughts: Data Recipes for Reasoning Models
- Kimi k1.5: Scaling Reinforcement Learning with LLMs
- Search-o1: Agentic Search-Enhanced Large Reasoning Models
- Understanding R1-Zero-Like Training: A Critical Perspective
- Stop Overthinking: A Survey on Efficient Reasoning for Large Language Models
- SimpleRL-Zoo: Investigating and Taming Zero Reinforcement Learning for Open Base Models in the Wild
Cite
@misc{chen2024do,
title = {{Do NOT Think That Much for 2+3=? On the Overthinking of o1-Like LLMs}},
author = {Chen, Xingyu and Xu, Jiahao and Liang, Tian and He, Zhiwei and Pang, Jianhui and Yu, Dian and Song, Linfeng and Liu, Qiuzhi and Zhou, Mengfei and Zhang, Zhuosheng and Wang, Rui and Tu, Zhaopeng and Mi, Haitao and Yu, Dong},
year = {2024},
doi = {10.48550/arxiv.2412.21187},
eprint = {2412.21187},
archivePrefix = {arXiv},
url = {https://doi.org/10.48550/arxiv.2412.21187}
}References
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