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Jiajun Xu
Graphics and Geometric Computing Group, Room 3-523, Information Technology Building (FIT), Tsinghua University
Email: xjj22@mails.tsinghua.edu.cn | Homepage: https://georginhsu.github.io
Research Interests
- My research interests lie in robotics, multimodal learning, and computer vision. Specifically, I’m passionate about dexterous hands and humanoids. I’m also interested in world models and VLA. My specific research interests include:
- Using video generation models as world models to provide an environment for robot reinforcement learning.
- Exploring the latent space of transformers and fine-tuning attention to reduce multimodal hallucinations.
- Chain-of-Thought (CoT) for large multimodal models.
Education
Tsinghua University, Department of Computer Science and Technology (Class of 2022–2026)
Beijing, China
September 2022 – June 2026
- GPA: 3.70/4.0
- Major Courses: Computer Language and Programming, Introduction to Computer Systems, Data Structures, Discrete Mathematics, Object-Oriented Programming, Software Engineering, Computer Graphics, Principles of Compilation, Principles of Signal Processing, Artificial Neural Network, Reinforcement Learning
- Supervisor: Shi-Min Hu
Publication
FuzzingRL: Reinforcement Fuzz-Testing for Revealing VLM Failures
Jiajun Xu*, Jiageng Mao*, Ang Qi, Weiduo Yuan, Alexander Romanus, Helen Xia, Vitor Campagnolo Guizilini, Yue Wang
CVPR 2026 (under review)
R-Bench: Graduate-level Multi-disciplinary Benchmarks for LLM & MLLM Complex Reasoning Evaluation
Meng-Hao Guo, Jiajun Xu, Yi Zhang, Jiaxi Song, Haoyang Peng, Yi-Xuan Deng, Xinzhi Dong, Kiyohiro Nakayama, Zhengyang Geng, Chen Wang, Bolin Ni, Guo-Wei Yang, Yongming Rao, Houwen Peng, Han Hu, Gordon Wetzstein, Shi-min Hu
arXiv (ICML 2025)
VisionReward: Fine-Grained Multi-Dimensional Human Preference Learning for Image and Video Generation
Jiazheng Xu*, Yu Huang*, Jiale Cheng, Yuanming Yang, Jiajun Xu, Yuan Wang, Wenbo Duan, Shen Yang, Qunlin Jin, Shurun Li, Jiayan Teng, Zhuoyi Yang, Wendi Zheng, Xiao Liu, Ming Ding, Xiaohan Zhang, Xiaotao Gu, Shiyu Huang, Minlie Huang, Jie Tang, Yuxiao Dong
AAAI 2026
Skills
Artificial Intelligence: PyTorch, Transformer Frameworks, Diffusion Model, build model frameworks and train models.
Programming Languages: C, C++, Python, Java, CUDA, Rust.
Research Experience
Geometry, Vision, and Learning (GVL) Laboratory, University of Southern California
Beijing, China
June 2025 – Present
- Engaged in research at the GVL Lab as a remote visiting student under the guidance of Assistant Professor Yue Wang.
- Leading the FuzzingRL project, aiming to systematically generate adversarially challenging queries by combining fuzz testing with reinforcement learning to reliably expose VLM vulnerabilities, coworking with Jiageng Mao (PhD candidate at GVL).
Graphics and Geometric Computing Group, Tsinghua University
Beijing, China
October 2024 – Present
- Conducted research in computer graphics, computer vision, and multimodal large models under the guidance of Professor Shi-Min Hu.
- Joined the R-Bench project under the guidance of Meng-Hao Guo (Postdoc at GGCG).
- Leading the Reasoning Attention project, collaborating with Meng-Hao Guo.
AI Research Intern, Beijing Zhipu AI Technology Co., Ltd.
Beijing, China
March 2024 – April 2025
- Actively involved in a video generation model project as a research intern.
- Experienced in distributed training with hundreds of GPUs and proficient in training with CogVLM.
Knowledge Engineering Group, Tsinghua University
Beijing, China
November 2023 – April 2025
- Participated in the multimodal group at KEG Lab, focusing on textual-visual graph research under the guidance of Associate Professor Yuxiao Dong.
- Joined the VisionReward project under the guidance of Jiazheng Xu (PhD candidate at KEG), aiming to develop a reward model for vision generative models.
Tsinghua Information Retriever Group, Tsinghua University
Beijing, China
May 2024 – October 2024
- Focused on research about Retrieval-Augmented Generation under the guidance of Assistant Professor Qingyao Ai.
- Constructed a RAG system with the LangChain framework.
Contest Experience
Tsinghua University Intelligent Agent Competition, Programmer
Beijing, China
May 2023
- Self-taught Python, Git, computer networks, etc., and collaborated with a team to develop an intelligent agent for the game “Minecraft” that can automatically perform player operations.
2024 COMAP Mathematical Contest in Modeling, Team Leader
Beijing, China
February 2024
- Planned and coordinated the team’s work, led the team to study the necessary knowledge, and received an Honorable Mention Award.
- Used multi-level analysis, K-means algorithm, and TOPSIS comprehensive evaluation method to model regional risk levels, producing a risk index directly usable by insurance companies.
Extracurricular Activities
Class Monitor of Class 22 in the Department of Computer Science and Technology, Tsinghua University
Beijing, China
September 2023 – Present
- Managed class affairs, assisted class teachers and counselors in class management, and organized various class and group activities.
- During tenure as class monitor, the class was awarded the title of Best Youth League Branch, the highest honor for a class in Tsinghua University.
Vice Minister of Department of Internal Contacts, Tsinghua University Science Association
Beijing, China
September 2023 – September 2024
- Coordinated and organized various scientific research competitions within the university.
- Established connections between different departments and the university science association.