About

Hello and welcome to my home page! Here I post my research background and other related experiences. My name is William Chang and in 2022 I graduated from University of Southern California with a B.A. in mathematics. Since 2023 Fall, I’ve been a PhD student at University of California, Los Angeles in Applied mathematics.

My research interests are rather diverse. It mainly span across mathematics and machine learning. Please see my papers below for more details on my work.

On the side I enjoy tutoring students. I’m willing to tutor students in math and physics at all levels (elementary, middle, high school, and university level as well). Feel free to email me chang314@g.ucla.edu if you want to book a session.

In my free time I like to practice Taekwondo and sing. Please feel free to check out my cover channel on youtube [@WilliamChangMusic]! Please also follow me on [Spotify]!

Please feel free to reach out to me for anything via chang314@g.ucla.edu!

Research

Publications

  1. Mobile Sensor Placement for the 3-Coverage Problem in Confined Geometries
    Haoyang Lyu, William Chang, Adrien Wiehs, Andrea Bertozzi, Paul Jeffrey Brantingham
    GTA3 workshop at IEEE International Conference on Data Mining, 2025

  2. Accelerating Low-Frequency Convergence for Limited-Angle DBT via Two-Channel Fidelity in PDHG
    Taro Iyadomi, Ricardo Parada, Anna Kim, Lily Jiang, Emil Sidky, William Chang
    Under Review at CT Meetings, 2026

  3. Decentralized Learning of Stackelberg Equilibrium in General-Sum Leader-Controller Markov Games
    Kenny Guo, Ricardo Parada, Helen Yuan, Larissa Xu, William Chang
    Under Review at International Conference in Machine Learning, 2026

  4. Policy Optimization for Corrupted Markov Decision Processes
    Khang Nguyen, Kenny Guo, David Yu, William Chang
    Under Review at International Conference in Machine Learning, 2026

  5. Best Arm Identification in Lipschitz Bandits: Uniform and Adaptive Strategies
    Khang Nguyen, Larissa Xu, Lily Jiang, William Chang
    Under Review at International Conference in Machine Learning, 2026

  6. Improved Multiplayer Bandit Algorithms for Bernoulli Noise
    Brook Chuang, William Chang
    Under Review at Conference in Decision and Control, 2025

  7. LinUCB in Multiplayer Information Asymmetric Contextual Bandits
    William Chang, Terry Lu
    Transactions of Machine Learning Research, 2025

  8. Mixing on Generalized Associahedra
    William Chang, Colin Defant, Daniel Frishberg
    Annals of Combinatorics, 2025

  9. DCM Bandits: Multiplayer Information Asymmetric Cascading Bandits For Multiple Clicks
    Andy Wang, Charlton Shih, William Chang
    Under Review at Transactions of Machine Learning Research

  10. Adversarially Robust Latent Bandits in Multiplayer Asymmetric Settings
    Helen Yuan, Kanzah Areej Jamil, Vanessa Jolie Pare, William Chang
    Under Review at Transactions of Machine Learning Research

  11. Multiplayer Information Asymmetric Linear Combinatorial Bandits
    Jacqueline Liu, Bree Chen, Xingjian Li, Yuxi Luo, William Chang
    Under Review at Transactions of Machine Learning Research

  12. The Learnability of the Multiplayer Adversarial Bandit Problem
    David Yu, Khang Nguyen, Daniel Yu, William Chang
    Under Review at Transactions of Machine Learning Research

  13. Heavy Tailed Reward Distributions for Multiplayer Bandits
    Daphne Feng, Ricardo Parada, Lily Jiang, Sophia Yi, William Chang
    Under Review at Transactions of Machine Learning Research

  14. Coordinating the Best Policy in Information Asymmetric MDPs
    Helen Yuan, Kanzah Areej Jamil, Chenzhang Zhao, Xingjian Li, William Chang
    Under Review at Transactions of Machine Learning Research

  15. Cooperative Information Asymmetric Multiplayer Learning in Markov Decision Processes
    Larissa Xu, King Bi, William Chang
    Under Review at Transactions of Machine Learning Research

  16. Multiplayer Information Asymmetric Bandits in Metric Spaces
    Aditi Kartik, William Chang
    Under Review at Transactions of Machine Learning Research

  17. Multi-Player Information Asymmetric Multiple Arm Identification
    Larissa Xu, Jasmine Nguyen, William Chang
    Under Review at Journal of Machine Learning Research

  18. Coordinating for Clicks: Learning in Multi-Agent Information Asymmetric Cascading Bandits
    Kenny Guo, Lily Jiang, Lune Chan, Sophia Yi, William Chang
    Under Review at Journal of Machine Learning Research

  19. Optimal Cooperative Multiplayer Learning Bandits with Noisy Rewards
    William Chang, Terry Lu
    Conference on Decision and Control, 2024

  20. Finite-Time Regret Bound of Multi-Agent Thompson Sampling
    Tianyuan Jin, Haolun Hsu, William Chang, Pan Xu
    Association for the Advancement of Artificial Intelligence, 2024

  21. Proceedings of the American Mathematical Society, Series B
    William Chang, Christopher S. Goodrich, Valentio Iverson, Khang Nguyen
    Proceedings of the American Mathematical Society, Series B

  22. No-Regret Online Reinforcement Learning with Adversarial Losses and Transitions
    Tiancheng Jin, Junyan Liu, Chloé Rouyer, William Chang, Chen-Yu Wei, Haipeng Luo
    Neural Information Processing Systems, 2023

  23. Bode Integral Limitation For Irrational Systems
    William Chang, Fariba Ariaei, Edmond Jonckheere
    International Federation of Automatic Control, 2023

  24. Closure of Certain Matrix Varieties and Applications
    William Chang, Robert Guralnick
    European Journal of Mathematics, 2023

  25. Finite-time self-similar rupture in a generalized elastohydrodynamic lubrication model
    William Chang, Hangjie Ji
    Under Review at Applied Mathematics Letters, 2023

  26. Stochastic Couplings and Bijections from the Symmetric Group to itself
    William Chang
    Mathematical Journal of Okayama University, 2023

  27. Compatibility in Ozsvath-Szabo’s bordered HFK via higher representations
    William Chang, Andrew Manion
    The Pacific Journal of Mathematics, 2023

  28. Approximation Capabilities of Neural Networks using Morphological Perceptrons and Generalizations
    William Chang, Hassan Hamad, Keith Chugg
    Asilomar Conference on Signals, Systems, and Computers, 2022

  29. Online Learning for Cooperative Multi-Player Multi-Armed Bandits
    William Chang, Mehdi Jafarnia-Jahromi, Rahul Jain
    IEEE Conference on Decision and Control, 2022

Mentored Research

I’m the founder of BruinML. I founded this group in January of 2024. Currently the president is Kenny Guo

I have had the privilege of mentoring many amazing students in research projects since Spring 2024. If you’re interested in a project please let me know chang314@g.ucla.edu.

  1. Accelerating Low-Frequency Convergence for Limited-Angle DBT via Two-Channel Fidelity in PDHG
    Taro Iyadomi, Ricardo Parada, Anna Kim, Lily Jiang, Emil Sidky, William Chang
    Under Review at CT Meetings, 2026

  2. Decentralized Learning of Stackelberg Equilibrium in General-Sum Leader-Controller Markov Games
    Kenny Guo, Ricardo Parada, Helen Yuan, Larissa Xu, William Chang
    Under Review at International Conference in Machine Learning, 2026

  3. Policy Optimization for Corrupted Markov Decision Processes
    Khang Nguyen, Kenny Guo, David Yu, William Chang
    Under Review at International Conference in Machine Learning, 2026

  4. Best Arm Identification in Lipschitz Bandits: Uniform and Adaptive Strategies
    Khang Nguyen, Larissa Xu, Lily Jiang, William Chang
    Under Review at International Conference in Machine Learning, 2026

  5. Improved Multiplayer Bandit Algorithms for Bernoulli Noise
    Brook Chuang, William Chang
    Under Review at Conference in Decision and Control, 2025

  6. LinUCB in Multiplayer Information Asymmetric Contextual Bandits
    William Chang, Terry Lu
    Transactions of Machine Learning Research, 2025

  7. Mixing on Generalized Associahedra
    William Chang, Colin Defant, Daniel Frishberg
    Annals of Combinatorics, 2025

  8. DCM Bandits: Multiplayer Information Asymmetric Cascading Bandits For Multiple Clicks
    Andy Wang, Charlton Shih, William Chang
    Under Review at Transactions of Machine Learning Research

  9. Adversarially Robust Latent Bandits in Multiplayer Asymmetric Settings
    Helen Yuan, Kanzah Areej Jamil, Vanessa Jolie Pare, William Chang
    Under Review at Transactions of Machine Learning Research

  10. Multiplayer Information Asymmetric Linear Combinatorial Bandits
    Jacqueline Liu, Bree Chen, Xingjian Li, Yuxi Luo, William Chang
    Under Review at Transactions of Machine Learning Research

  11. The Learnability of the Multiplayer Adversarial Bandit Problem
    David Yu, Khang Nguyen, Daniel Yu, William Chang
    Under Review at Transactions of Machine Learning Research

  12. Heavy Tailed Reward Distributions for Multiplayer Bandits
    Daphne Feng, Ricardo Parada, Lily Jiang, Sophia Yi, William Chang
    Under Review at Transactions of Machine Learning Research

  13. Coordinating the Best Policy in Information Asymmetric MDPs
    Helen Yuan, Kanzah Areej Jamil, Chenzhang Zhao, Xingjian Li, William Chang
    Under Review at Transactions of Machine Learning Research

  14. Cooperative Information Asymmetric Multiplayer Learning in Markov Decision Processes
    Larissa Xu, King Bi, William Chang
    Under Review at Transactions of Machine Learning Research

  15. Multiplayer Information Asymmetric Bandits in Metric Spaces
    Aditi Kartik, William Chang
    Under Review at Transactions of Machine Learning Research

  16. Multi-Player Information Asymmetric Multiple Arm Identification
    Larissa Xu, Jasmine Nguyen, William Chang
    Under Review at Journal of Machine Learning Research

  17. Coordinating for Clicks: Learning in Multi-Agent Information Asymmetric Cascading Bandits
    Kenny Guo, Lily Jiang, Lune Chan, Sophia Yi, William Chang
    Under Review at Journal of Machine Learning Research

  18. Optimal Cooperative Multiplayer Learning Bandits with Noisy Rewards
    William Chang, Terry Lu
    Conference on Decision and Control, 2024

  19. Finite-Time Regret Bound of Multi-Agent Thompson Sampling
    Tianyuan Jin, Haolun Hsu, William Chang, Pan Xu
    Association for the Advancement of Artificial Intelligence, 2024

  20. Proceedings of the American Mathematical Society, Series B
    William Chang, Christopher S. Goodrich, Valentio Iverson, Khang Nguyen
    Proceedings of the American Mathematical Society, Series B

Teaching

These are the classes I’ve taught, the resources I provided, as well as the teaching evalutions I received in reverse chronological order.

2024 Fall Quarter Math 131A Real Analysis
Course Plan [PDF]
Homework Solutions [PDF]
Teaching Evaluations [Section 1A]

2024 Fall Quarter Math 134 Linear and Nonlinear Systems of Differential Equations
Syllabus [PDF]
Homework Solutions [PDF]
Teaching Evaluations [Section 1A]

2024 Spring Quarter Math 156 Machine Learning
Syllabus [PDF]
Homework Solutions [PDF]
Teaching Evaluations [Section 1A]

2024 Winter Quarter Math 32B Calculus of Several Variables
Syllabus [PDF]
Homework Solutions [PDF]
Teaching Evaluations [Section 1E] [Section 1F]

2023 Fall Quarter Math 31A Differential and integral calculus
Syllabus [PDF]
Homework Solutions [PDF]
Teaching Evaluations [Section 1C], [Section 1D]

I’ve also taught at the UCLA Math Circle since 2023 Fall Quarter

UCLA Qualifying Exams

These are the Qualifying Exams I passed:

Basic Exam: 2023 Fall

Geometry/Topology: 2024 Spring

Applied Differential Equations: 2023 Fall