Litu Ou

Litu Ou

Long-context and long-horizon language models

About

I am a PhD student at the Institute for Language, Cognition and Computation (ILCC), University of Edinburgh, advised by Prof. Mirella Lapata. I work on long-context and long-horizon language models, with a focus on how LLMs organize, retrieve, and reason over information at scale. My recent work studies structured representations for long-form documents and narratives, as well as retrieval, reasoning, and test-time control for web agents. Previously, I interned at Tongyi Lab, where I worked on the Tongyi DeepResearch project.

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News

  1. 2026.08
    Two papers accepted to EMNLP 2026.
  2. 2026.05
    One paper accepted to SIGIR 2026.
  3. 2026.05
    BrowseConf accepted to Findings of ACL.

Publications and Preprints

  1. Storyline Trees: Hierarchical Representations for Long-Form Narratives
    Litu Ou, Mirella Lapata - Findings of EMNLP, 2026
  2. Revisiting Text Ranking in Deep Research
    Chuan Meng, Litu Ou, Sean MacAvaney, Jeff Dalton - SIGIR, 2026
  3. Uncertainty-Aware Gradient Signal-to-Noise Data Selection for Instruction Tuning
    Zhihang Yuan, Chengyu Yue, Long Huang, Litu Ou, Lei Shi - EMNLP, 2026
  4. Tongyi DeepResearch Technical Report
    Tongyi DeepResearch Team, including Litu Ou - arXiv, 2025
  5. BrowseConf: Confidence-Guided Test-Time Scaling for Web Agents
    Litu Ou, Kuan Li, Huifeng Yin, Liwen Zhang, Zhongwang Zhang, Xixi Wu, Rui Ye, Zile Qiao, Yong Jiang, Pengjun Xie, Fei Huang, Jingren Zhou - Findings of ACL, 2026
  6. WebSailor-V2: Bridging the Chasm to Proprietary Agents via Synthetic Data and Scalable Reinforcement Learning
    Kuan Li, Zhongwang Zhang, Huifeng Yin, Rui Ye, Yida Zhao, Liwen Zhang, Litu Ou, Dingchu Zhang, Xixi Wu, Jialong Wu, Xinyu Wang, Zile Qiao, Zhen Zhang, Yong Jiang, Pengjun Xie, Fei Huang, Jingren Zhou - ICLR, 2026
  7. ReSum: Unlocking Long-Horizon Search Intelligence via Context Summarization
    Xixi Wu, Kuan Li, Yida Zhao, Liwen Zhang, Litu Ou, Huifeng Yin, Zhongwang Zhang, Xinmiao Yu, Dingchu Zhang, Yong Jiang, Pengjun Xie, Fei Huang, Minhao Cheng, Shuai Wang, Hong Cheng, Jingren Zhou - arXiv, 2025
  8. WebSailor: Navigating Super-human Reasoning for Web Agent
    Kuan Li, Zhongwang Zhang, Huifeng Yin, Liwen Zhang, Litu Ou, Jialong Wu, Wenbiao Yin, Baixuan Li, Zhengwei Tao, Xinyu Wang, Weizhou Shen, Junkai Zhang, Dingchu Zhang, Xixi Wu, Yong Jiang, Ming Yan, Pengjun Xie, Fei Huang, Jingren Zhou - arXiv, 2025
  9. ToLeaP: Rethinking Development of Tool Learning with Large Language Models
    Haotian Chen, Zijun Song, Boye Niu, Ke Zhang, Litu Ou, Yaxi Lu, Zhong Zhang, Xin Cong, Yankai Lin, Zhiyuan Liu, Maosong Sun - arXiv, 2025
  10. Context-Aware Hierarchical Merging for Long Document Summarization
    Litu Ou and Mirella Lapata - Findings of ACL, 2025
  11. Open-Source vs Close-Source: The Context Utilization Challenge
    Litu Ou - ICLR Blogpost Track, 2025
  12. Chain-of-Thought Hub: A Continuous Effort to Measure Large Language Models' Reasoning Performance
    Yao Fu, Litu Ou, Mingyu Chen, Yuhao Wan, Hao Peng, Tushar Khot - ICML, 2023
  13. Specializing Smaller Language Models towards Multi-Step Reasoning
    Yao Fu, Hao Peng, Litu Ou, Ashish Sabharwal, Tushar Khot - ICML Oral/Poster, 2023

Research Experience

  1. 2025.09 - Present
    University of Edinburgh, Institute for Language, Cognition and Computation

    Researching long-context and long-horizon LLM systems, supervised by Prof. Mirella Lapata.

  2. 2025.06 - 2025.09
    Research Intern, Tongyi DeepResearch Team

    Worked on post-training, test-time control, and scalable RL pipelines for LLM-based web agents.

  3. 2024.08 - 2025.05
    Research Intern (Remote), Tsinghua University

    Worked on tool learning and multi-step reasoning with large language models.

  4. 2023.06 - 2024.11
    Research Assistant, University of Edinburgh

    Worked on retrieval-enhanced and hierarchical methods for faithful book-length summarization.

Academic Service / Teaching

  • Conference Reviewer: NeurIPS 2026 Evaluations and Datasets Track
  • Workshop Reviewer: LASS Workshop at CIKM 2026; LLA Workshop at COLM 2026; LLA Workshop at ICLR 2026
  • Teaching Assistant: Foundations of Natural Language Processing, University of Edinburgh (January-May 2026)