Hao (Jack) BAI

Hao (Jack) BAI

CS M.S. Candidate

University of Illinois, Urbana Champaign

Hi, there! I’m Jack. I’m an M.S. student in Computer Science at University of Illinois Urbana-Champaign, where I’m fortunate to be advised by Prof. Heng Ji. The core of my research is in robust machine learning towards autonomous intelligence. I work on this problem upon two levels:

  • I study representation learning for modern vision/language models (especially for causal attention) to understand & interpret what and how the models are learning.
  • Based on these understanding of foundation models, I study closed-loop learning algorithms like reinforcement learning and self-supervised learning upon these models.

Methodologies I often use to enhance the approaches often include making interactions with agents as well as retriving external knowledge as grouding signals.

Bio: Jack Bai is an M.S. student in Computer Science at UIUC, advised by Prof. Heng Ji, and a visiting scholar at BAIR, advised by Prof. Yi Ma and Prof. Sergey Levine. Before master’s, he obtained a dual degree from Zhejiang University and UIUC in Computer Engineering. During those wonderful years, he interned at MSR advised by Dr. Shilin He, and participated in the Alexa SocialBot Challenge advised by Prof. Chengxiang Zhai.

In my spare time, I do car racing (mainly drifting) and play guitar.

  • Representation Learning
  • Reinforcement Learning
  • Information Retrieval
  • MS in Computer Science, 2025

    University of Illinois, Urbana Champaign

  • BS in Computer Engineering, 2023

    University of Illinois, Urbana-Champaign


  • I don’t have bandwidth to collaborate with any undergraduate interns this semester (SP2024).
  • If you’re a graduate student, and you’re interested in language model interpretability, reach out to my email.

Core Publications

The publications are not complete. Some work are protected and some work are still in the publication process.

White-Box Transformers via Sparse Rate Reduction: Compression Is All There Is? (JMLR)
CharmBana: Progressive Responses with Real-Time Internet Search for Knowledge-Powered Conversations (WSDM-24)
Social Commonsense-Guided Search Query Generation for Open-Domain Knowledge-Powered Conversations (EMNLP-23)



In a discussion with Prof. Raymond Yeh, he mentioned that the importance of interpretability is dependent on performance. If we can already achieve good performance, interpretability is not a big deal. The importance of interpretability appears when something is not good enough. When this happens, we want to understand how the system works, in order to improve the system more efficienctly.

If we don’t go this way, interpretability usually decreases performance, because interpretability is intrinsically costly. Black-box models are called black-box because opening the box is intrinsically unsupported, thus trying to interpret black-box models always leads to extra effort, which potentially drags the performance down.

This is why principled methods are valuable: principled methods are intrinsically interpretable. When the method has a bad performance, it will not be published; when the method has a good performance, it’s interpretable. Principled methods like CRATE and Information Band Theory are good examples of this claim. This is the reason why I prefer principled methods compared to purely statistical methods.

Value of Research

In a discussion with Prof. Chengxiang Zhai, he mentioned the key value of research across all subjects: a valuable research should either propose a new question or propose a new solution to an existing question. A new question is usually more difficult to define, because the value of the question is highly dependent on both academic and real-world recognization. The value of a solution is evaluated by metrics, which are defined by the question, but the value of a question is evaluated by human, who is defined by physics.

Going either way, it’s inevitable to do comprehensive survey before designing any methods. After proposing an idea, it’s extremely important to do comprehensive survey on the topic to refine the idea and method. It’s also important to give presentations on the idea to people from various backgrounds, including home-area specialists on the method feasibility, away-area specialists on approach value, and out-of-area audience on real-life value. For example, when you want to use ML-based methods to develop a new drug, you need home-area (ML) guys to look at your method, away-area (chemistry) guys to assess the value of the approach, and out-of-area audience (like your parents) to comment on high-level real-life value.

Under such framework, quick publication is not a good idea for a real researcher, because they lack a ton of considerations and real-life applications. As suggested by Prof. Heng Ji, when she assesses a student, quality is much more important than quantity. A student must have 1st authorship paper published at top-tier conference, but as long as he has some, the number becomes insignificant. Having publishments means the student has participated in the complete process of a research, and having a solid and creative publishment means the student is strict and creative. On the other hand, having too many publications is extremely confusing to PIs when they view the CV and may lead to an impression that the student focuses more on fame per se instead of research. This kind of impression is extremely bad and usually causes an instinctive refusion.

On Model Edit by Changing Weights Directly

I’m a strongly against the idea to edit model weights directly. Editing a neuron (or a layer) changes not only this fact, but potentially all the facts, and it inadvertently hurts the model representation. The only promising way to change is to only change a single neuron that’s controlling this specific fact, but research has shown that transformer models try to compress representations, so it’s not possible for find orthogonal subspaces of facts for neurons.

The Three Circles

Prof. Chengxiang Zhai proposed the three circles when we do research: the Passion circle, the Benefit circle and the Resource circle. These circles construe what ideas we choose, how valuable the idea is, and whether we can achieve them. Having good circles reduces peer pressure significantly, and when looking back, the person usually have already achieved a lot and will not feel like a loser.

The passion circle means the intrinsic passion of a person doing research, and will determine the ending place of a person at academy. Everyone doing research should keep asking himself: do I really love doing this research? Why did I start this research? Can I really take it as my job? These are super important questions as they directly contributes to passion, and passion leads to consistency and focus. With passion, peer pressure will easily be waived as the researcher begins to focus on the research per se, instead of focusing on how many papers he has published. People who reach this level usually do very well in any field.

The benefit circle means the value of the research. A good research usually tackles a very important problem in society and construes of no less than 3 papers published at top-tier conferences. Having multiple papers on one topic is usually an excellent signal because the project is proved to be recognized and has great potential, which is usually beneficial to the society or academy.

The resource circle limits what a researcher is good at. As an undergraduate student, it’s usually okay to explore around and see where his strength is. However, graduate researchers are required to find his own strengths and weaknesses in order to propose a suitable project. An eligible researcher should always utilize his strength for research while still learn to make up his weakness. If someone is not good at abstract thinking, asking him to do pure math research kills him; if someone loves abstract deduction, doing practical projects makes him sleepy. If you don’t have lots of GPUs, avoid doing experiments with LM pretraining and LLM fine-tuning - this is not gonna work if you don’t have enough computational resources, so choose ideas wisely. This is not even about going out of your comfort zone, it’s how physics works. Concurrently, making up the shortness is important because although he can avoid creating knowledge related to his weaknesses, he can’t avoid reading them. When encountering a paper that is hard to understand, try not to skip it and make up the weakness using that paper.