Jiayu Liu 刘家毓

👋 Welcome to my homepage! 🥂
I’m Jiayu Liu 刘家毓, an undergraduate Computer Science student at HKUST. I was an exchange student at UIUC in Spring 2026 and am currently an undergraduate research intern advised by Prof. Heng Ji and Prof. Dilek Hakkani-Tür. Previously, I was supervised by Prof. Yangqiu Song and Prof. Yiren Fung at HKUST.

My research broadly focuses on evaluating and building LLM agents that are both adaptive and reliable. In particular, my current interests center on two aspects:

• Adaptability: Evaluating and building LLM agents that plan, explore, and adapt in changing environments, including tool use and cost-aware planning [PlanBench-XL, CostBench], planning under evolving constraints [AdaPlanBench], and proactive exploration [AdaExploreBench].

• Reliability: Understanding whether LLMs can reliably perceive uncertainty expressed in language [MarPT], reason under imperfect or noisy external information [NAACL], and faithfully express their own confidence [MarConf].

Previously, I also studied LLM reasoning, from diagnosing fundamental failures [RFMBench] to developing post-training methods [Multirole-R1].

🎓 I am currently seeking PhD opportunities in Computer Science for Fall 2027. If you think my research background and interests may be a good fit for your group, I would be very grateful to hear from you.

I am also always happy to connect with fellow students and researchers. Feel free to reach out for academic discussions, research ideas, or potential collaborations!

📫 Contact: jliufv@connect.ust.hk

🔥 News

📖 Selected Publications

Selected first-author and co-first-author papers are listed below, ordered by year and venue. See Google Scholar for the full publication list. ^* denotes equal contribution.

EMNLP 2026

PlanBench-XL: Evaluating Long-Horizon Planning of LLM Tool-Use Agents in Large-Scale Tool Ecosystems

Jiayu Liu^*, Qihan Lin^*, Cheng Qian, Rui Wang, Emre Can Acikgoz, Xiaocheng Yang, Qing Zong, Jiateng Liu, Zhenhailong Wang, Xiusi Chen, Heng Ji, Dilek Hakkani-Tür

arXiv HF Daily Papers Code

EMNLP 2026

Rethinking Prospect Theory for LLMs: Revealing the Instability of Decision-Making under Epistemic Uncertainty

Rui Wang^*, Qihan Lin^*, Jiayu Liu^*, Qing Zong, Tianshi Zheng, Dadi Guo, Haochen Shi, Peixuan Han, Weiqi Wang, Yangqiu Song

arXiv Code

Findings of EMNLP 2026

NAACL: Noise-AwAre Verbal Confidence Calibration for LLMs in RAG Systems

Jiayu Liu^*, Rui Wang^*, Qing Zong, Qingcheng Zeng, Tianshi Zheng, Haochen Shi, Dadi Guo, Baixuan Xu, Chunyang Li, Yangqiu Song

arXiv HF Daily Papers Code

COLM 2026

AdaPlanBench: Evaluating Adaptive Planning in Large Language Model Agents under World and User Constraints

Jiayu Liu, Cheng Qian, Zhenhailong Wang, Bingxuan Li, Jiateng Liu, Heng Wang, Jeonghwan Kim, Yumeng Wang, Xiusi Chen, Yi R. Fung, Heng Ji

arXiv HF Daily Papers Code

ACL 2026

CostBench: Evaluating Multi-Turn Cost-Optimal Planning and Adaptation in Dynamic Environments for LLM Tool-Use Agents

Jiayu Liu, Cheng Qian, Zhaochen Su, Qing Zong, Shijue Huang, Bingxiang He, Yi R. Fung

arXiv HF Daily Papers Code

ACL 2026

Mathematical Proof as a Litmus Test: Revealing Failure Modes of Advanced Large Reasoning Models

Dadi Guo^*, Jiayu Liu^*, Zhiyuan Fan, Zhitao He, Haoran Li, Yumeng Wang, Yi R. Fung

arXiv Code

ICLR 2026

Diversity-Enhanced Reasoning for Subjective Questions

Yumeng Wang^*, Zhiyuan Fan^*, Jiayu Liu^*, Jen-tse Huang, Yi R. Fung

arXiv HF Daily Papers Code

ACL 2025

Revisiting Epistemic Markers in Confidence Estimation: Can Markers Accurately Reflect Large Language Models' Uncertainty?

Jiayu Liu, Qing Zong, Weiqi Wang, Yangqiu Song

ACL Anthology arXiv Code

FEVER 2024

GProofT: A Multi-dimension Multi-round Fact Checking Framework Based on Claim Fact Extraction

Jiayu Liu^*, Junhao Tang^*, Hanwen Wang^*, Baixuan Xu, Haochen Shi, Weiqi Wang, Yangqiu Song

ACL Anthology Code

arXiv preprint · 2026

AdaExploreBench: Benchmarking LLM Agents for Proactive Exploration and Test-time Adaptation in Evolving Environments

Rui Wang^*, Zishen Lai^*, Jiayu Liu^*, Cheng Qian, Jeonghwan Kim, Heng Wang, Xuejun Zhang, Jiateng Liu, Bingxuan Li, Shujin Wu, Qing Zong, Tianshi Zheng, Chunyang Li, Qihan Lin, Chen Li, Dadi Guo, Xiusi Chen, Yangqiu Song

arXiv HF Daily Papers Project page Code Dataset

🧾 Academic & Community Service

• Founder, HKUST UGAI Lab
• Reviewer: IJCAI 2025, COLM 2026, and ARR (since May 2026)
• HKUST COMP and CPEG Mentor 2024/25
• HKUST PMP group mentor
• IT Secretary of Chinese Folks and Arts Society, HKUST

🎤 Invited Talks

• “Towards Cost-aware Tool Integrated Planning.” Invited talk at Natural Language Processing and Multimodal Intelligence Platform (Post), Host: Wenjie Li.

Misc

In my spare time, I’m passionate about music and sports. I play the piano and violin, and I also enjoy singing and sharing my performances on social media. For sports, football is my absolute favorite—I’m a member of both the HKUST Mainland Students Football Team and the Guangdong Experimental High School Football Team, and I truly cherish the memories and friendships from those times. I also enjoy sailing at sea, and yachting makes me feel an incredible sense of freedom.

Feel free to check out some of my music:

• Me playing Chopin’s Fantaisie-Impromptu: YouTube
• Me performing the Chinese ballad Why Are the Flowers So Red: YouTube
• My singing profile: WeSing (全民k歌) (~200 fans)