CV

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• PhD student in Department of Computer Science in University of Virginia, Sep 2024 – May 2029
  • Major courses: Natural Language Processing, Learning for Interactive Robots, Machine learning, Software logic, etc.
• B.S. in School of Mathematical Science, Peking University, Sep 2020 – Jul 2024
  • Major courses: Mathematical Analysis; Probability Theory (H); Applied Stochastic Processes (Honor); Mathematical Statistics, etc.

Research experience

• Sequential Intelligence Lab, University of Virginia (Aug.2024-Now)
  • Conducting theoretical research on convergence analysis of reinforcement learning algorithms under supervision of Prof. Shangtong Zhang
  • Developing mathematical frameworks for proving $L^2$ and almost sure convergence of reinforcement learning methods
  • Analyzing convergence rates of stochastic approximation algorithms with Markovian noise
• Mathematics in Lean, Peking University (Aug.2023-Jun.2024)
  • Led by Prof. Zaiwen Wen, formalized complex mathematical proofs using formal verification system lean4
  • Implemented rigorous mathematical theorems in computer-assisted proof systems, focusing on complex analysis
• Dynamic System, Peking University (Jun.2022-Feb.2023)
  • Conducted research in dynamical systems theory under guidance of Prof. Zhiqiang Li
  • Analyzed mathematical properties of expanding maps and conformal fractals
  • Presented theoretical findings on conformal dynamics in research seminars

Intern experience

• Quantitative Research Intern, Founder Securities (Jul 2023 – Sep 2023)
  • Developed theoretical models for financial markets under supervision of Dr. Song Hao
  • Applied statistical learning theory to analyze market behavior
  • Implemented and validated mathematical models for option pricing

Publications

[arXiv 2026]Almost Sure Convergence Rates of Stochastic Approximation and Reinforcement Learning via a Poisson-Moreau Drift Xinyu Liu, Zixuan Xie, Shangtong Zhang

[arXiv 2026]MathlibPR: Pull Request Merge-Readiness Benchmark for Formal Mathematical Libraries Zixuan Xie*, Xinyu Liu*, Shangtong Zhang

[arXiv 2026]Beyond Linear Attention: Softmax Transformers Implement In-Context Reinforcement Learning Zixuan Xie, Xinyu Liu, Claire Chen, Shuze Daniel Liu, Rohan Chandra, Shangtong Zhang

[arXiv 2026]Convergence and Emergence of In-Context Reinforcement Learning with Chain of Thought Zixuan Xie, Xinyu Liu, Shangtong Zhang

[ICML 2026]Offline Two-Player Zero-Sum Markov Games with KL Regularization Claire Chen, Yuheng Zhang, Xinyu Liu, Zixuan Xie, Shuze Daniel Liu, Nan Jiang

[ICML 2026]MathlibLemma: Folklore Lemma Generation and Benchmark for Formal Mathematics Xinyu Liu, Zixuan Xie, Amir Moeini, Claire Chen, Shuze Daniel Liu, Yu Meng, Aidong Zhang, Shangtong Zhang

[arXiv 2025]Extensions of Robbins-Siegmund Theorem with Applications in Reinforcement Learning Xinyu Liu, Zixuan Xie, Shangtong Zhang

[NeurIPS 2025]Finite Sample Analysis of Linear Temporal Difference Learning with Arbitrary Features Zixuan Xie*, Xinyu Liu*, Rohan Chandra, Shangtong Zhang

[ICML 2025]Linear $Q$-Learning Does Not Diverge in $L^2$: Convergence Rates to a Bounded Set Xinyu Liu*, Zixuan Xie*, Shangtong Zhang

[arXiv 2024]Almost Sure Convergence Rates and Concentration of Stochastic Approximation and Reinforcement Learning with Markovian Noise Xiaochi Qian*, Zixuan Xie*, Xinyu Liu*, Shangtong Zhang

Teaching Assistantships

• Reinforcement Learning (Fall 2025, University of Virginia): hosted office hours and graded assignments.

Peer Review

• Reviewer for International Conference on Machine Learning (ICML) 2026 (Sliver Reviewer)
• Reviewer for Reinforcement Learning Conference (RLC) 2026
• Emergency Technical Reviewer for Reinforcement Learning Conference (RLC) 2025
• Emergency Reviewer for International Conference on Learning Representations (ICLR) 2026
• Reviewer for International Conference on Artificial Intelligence and Statistics (AISTAT) 2026

Skills and Awards

• Technologies: Python(3 years), C&C++(1 year), Latex(3 years), lean4(2 years), Mathematica/MATLAB(2 years)
• Language: Mandarin, English
• No.14 Chinese College Mathematics Competition, 1st class (National Level)
• Second Prize, 35th Chinese Mathematical Olympiad Final Round (2019)
• Gold Medal, Olympiad of Metropolities (2019)