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!

Multiplayer Bandits

1. The Learnability of the Multiplayer Adversarial Bandit Problem
   David Yu, Khang Nguyen, Daniel Yu, William Chang
   Under review at Conference in Decision and Control 2025

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

3. Heavy Tailed Reward Distributions for Multiplayer Bandits
   Daphne Feng, Ricardo Parada, Lily Jiang, Sophia Yi, William Chang
   Under review at Conference in Decision and Control 2025

4. Coordinating the Unknown Lipschitz Constant in Multiplayer Bandits,
   Ricardo Parada, Chenzhang Zhao, William Chang
   Under review at Conference in Decision and Control 2025

5. Multiplayer Information Asymmetric Bandits in Metric Spaces [PDF]
   William Chang, Aditi Karthik
   Under review at Transactions of Machine Learning Research

6. Multi-Player Information Asymmetric Multiple Arm Identification [PDF]
   Larissa Xu, Jasmine Nguyen, William Chang
   Under review at Journal of Machine Learning Research

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

8. Multiplayer Information Asymmetric Contextual Bandits [PDF]
   William Chang, Terry Lu
   Transactions of Machine Learning Research 2025

9. Optimal Cooperative Multiplayer Learning Bandits with Noisy Rewards and No Communication [PDF]
   William Chang, Terry Lu
   IEEE Conference on Decision and Control, 2024

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

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

Markov Decision Processes

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

Control Theory

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

Neural Network Theory

8. Approximation Capabilities of Neural Networks using Morphological Perceptions and Generalizations [PDF]
   William Chang, Hassan Hamad, Keith Chugg
   Asilomar conference on signals, systems, and computers, 2022

Computer Vision

9. Mixup to the Random Extreme and Its Performances in Robust Image Classification [PDF]
   Jackie Chen, Qianjing Chen, William Chang, Haohan Wang
   Transactions on Machine Learning Research, 2023

Domain Adaptation

10. Understanding Domain Adaptation in the Lens of Causality[PDF]
    William Chang, Haohan Wang
    Under review at Causal Learning and Reasoning, 2024

Mixing

11. Mixing on Generalized Associahedra
    William Chang, Colin Defant, Daniel Frishberg
    Under Review at International Symposium on Algorithms and Computation, 2023

Differential Equations

12. Finite-time singularities in a generalized elastohydrodynamic lubrication equation [PDF]
    William Chang, Hangjie Ji
    Under Review at Applied Mathematics Letters, 2023

Geometry

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

Algebra

14. Closure of Certain Matrix Varieties and Applications [PDF]
    William Chang, Robert Guralnick
    European Journal of Mathematics

Combinatorics

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

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. Below are some of my most common areas (and I’m looking to expand this by a lot). If you’re interested in a project please let me know chang314@g.ucla.edu.

Multiplayer Bandits
We study the information asymmetry mutliplayer bandits applied to various bandit problems. One of my top students wrote a blog on this after he submitted the Cascading paper. See here for more details.

1. The Learnability of the Multiplayer Adversarial Bandit Problem
   David Yu, Khang Nguyen, Daniel Yu, William Chang
   Under review at Conference in Decision and Control 2025

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

3. Heavy Tailed Reward Distributions for Multiplayer Bandits
   Daphne Feng, Ricardo Parada, Lily Jiang, Sophia Yi, William Chang
   Under review at Conference in Decision and Control 2025

4. Coordinating the Unknown Lipschitz Constant in Multiplayer Bandits,
   Ricardo Parada, Chenzhang Zhao, William Chang
   Under review at Conference in Decision and Control 2025

5. Multiplayer Information Asymmetric Bandits in Metric Spaces [PDF]
   William Chang, Aditi Karthik
   Under review at Transactions of Machine Learning Research

6. Multi-Player Information Asymmetric Multiple Arm Identification [PDF]
   Larissa Xu, Jasmine Nguyen, William Chang
   Under review at Journal of Machine Learning Research

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

8. Multiplayer Information Asymmetric Contextual Bandits [PDF]
   William Chang, Terry Lu
   Transactions of Machine Learning Research 2025

9. Optimal Cooperative Multiplayer Learning Bandits with Noisy Rewards and No Communication [PDF]
   William Chang, Terry Lu
   IEEE Conference on Decision and Control, 2024

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

These are the Qualifying Exams I passed:

Basic Exam: 2023 Fall

Geometry/Topology: 2024 Spring

Applied Differential Equations: 2023 Fall