Search-o1: Agentic Search-Enhanced Large Reasoning Models
Written for the Research library (claude-opus-5-5) from the paper text. Original — aclanthology.org/2025.emnlp-main.276.pdf
Summary
Large reasoning models (LRMs) such as OpenAI-o1 or QwQ produce long chains of thought, and those chains often run into gaps in what the model knows. The authors measure this through hedging words: on GPQA diamond, QwQ-32B-Preview writes "perhaps" about 30 times per answer. Search-o1 addresses this without extra training. The model is prompted to write its own search queries whenever it gets stuck while reasoning, and it can search again as many times as it needs within one session. Retrieved web documents tend to be long and noisy, so a separate Reason-in-Documents step first checks them against the current query and the reasoning so far. Only a short, relevant result goes back into the chain. The authors test it on reasoning tasks in science, math and coding, and on six open-domain QA benchmarks. Search-o1 beats direct reasoning, standard RAG and agentic RAG baselines, and its overall GPQA score is higher than that of human experts. The work shows that letting LRMs use tools while they answer can make them more reliable, and it points toward deep-research systems.
Key points
- Approach: two parts on top of an LRM, driven by prompts rather than fine-tuning. The first is an agentic RAG loop in which the model decides when to search and what to search for. The second is Reason-in-Documents, which filters retrieved text before it enters the reasoning chain. Code: github.com/RUC-NLPIR/Search-o1.
- GPQA extended set vs. human experts: Search-o1 scores 57.9 overall, 68.7 in physics and 69.5 in biology. It still trails chemists in chemistry (40.7 vs. 72.6).
- Open-domain QA (NQ, TriviaQA, HotpotQA, 2WikiMultihopQA, MuSiQue, Bamboogle; EM/F1): on multi-hop tasks, average EM is 29.6% higher than RAG-QwQ-32B and 5.3% higher than RAgent-QwQ-32B. On single-hop tasks, agentic search gives QwQ-32B almost no gain.
- Retrieval depth and backbones: with just one retrieved document, Search-o1 already beats direct reasoning and standard RAG that use ten. The gains also hold with Sky-T1-32B-Preview and DeepSeek-R1-Distill-Qwen-32B as backbones.
- Limitations the authors state: search is the only tool so far, with no training-based (fine-tuning or RL) optimisation, and multimodal models are not yet covered.
Cited by
- Towards Reasoning Era: A Survey of Long Chain-of-Thought for Reasoning Large Language Models
- Search-R1: Training LLMs to Reason and Leverage Search Engines with Reinforcement Learning
- R1-Searcher: Incentivizing the Search Capability in LLMs via Reinforcement Learning
- Large Language Models for Information Retrieval: A Survey
Cite
@inproceedings{li2025search,
title = {{Search-o1: Agentic Search-Enhanced Large Reasoning Models}},
author = {Li, Xiaoxi and Dong, Guanting and Jin, Jiajie and Zhang, Yuyao and Zhou, Yujia and Zhu, Yutao and Zhang, Peitian and Dou, Zhicheng},
booktitle = {Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing},
year = {2025},
doi = {10.18653/v1/2025.emnlp-main.276},
url = {https://doi.org/10.18653/v1/2025.emnlp-main.276}
}References
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