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Hi, I'm Yibo (Jacky) Zhang


photo taken in Vancouver, Canada
I am a PhD student in the Department of Computer Science at Stanford University, where I am fortunate to be advised by Sanmi Koyejo. I am also a member of the (MBCT) program under Wu Tsai Neurosciences Institute.

I'm interested in solving fundamental AI problems through theoretical research that leads to real-world solutions.

Currently, my research focuses on learning in systems composed of dynamically and stochastically interacting components. Pease see my selected works for more details.

Education Stanford University
  • PhD Student - Department of Computer Science (present)
University of Illinois at Urbana-Champaign
  • M.S. in Computer Science (2022)
University of Science and Technology of China
  • B.E. in Computer Science (2019)
Publications & Preprints
(*eqaul contribution)
Selected Is Backpropagation Optimal? When Synthetic Gradients Improve Sample Efficiency [ pdf ]
Yibo Jacky Zhang, Zeyu Tang, Sanmi Koyejo.
  • Backpropagation is the default learning rule for artificial neural networks and is often treated as the settled credit assignment approach whenever differentiability is available.
  • In this work, we revisit this convention through a theoretical lens of sample efficiency. We characterize the conditions under which synthetic gradients can achieve a lower gradient-estimation mean squared error than backpropagation. We construct examples illustrating that this sample efficiency advantage can be arbitrarily large.
Aligning Compound AI Systems via System-level DPO [ pdf ]
Xiangwen Wang*, Yibo Jacky Zhang*, Zhoujie Ding, Katherine Tsai, Sanmi Koyejo.
Neural Information Processing Systems (NeurIPS), 2025.
  • Compound AI systems, comprising multiple interacting components such as LLMs and diffusion models, have demonstrated improvements compared to single models. However, aligning compound AI systems to human preferences is challenging.
  • We propose a principled framework (SysDPO) for aligning all components in a compound AI system as a cohesive whole.
A Framework for Objective-Driven Dynamical Stochastic Fields [ pdf ]
Yibo Jacky Zhang, Sanmi Koyejo.
  • It is challenging to describe complex systems composed of interacting and dynamic components. In particular, it becomes more challenging as these components in the system exhibit objective-driven behaviors.
  • This paper develops a formal and elegant description of such systems using a field-theoretic language inspired by physics. The proposed theoretical framework is referred to as intelligent fields.
List of All Is Backpropagation Optimal? When Synthetic Gradients Improve Sample Efficiency [ pdf ]
Yibo Jacky Zhang, Zeyu Tang, Sanmi Koyejo.
Preprint, 2026.
Latent Adversarial Regularization for Offline Preference Optimization [ pdf ]
Enyi Jiang, Yibo Jacky Zhang, Yinglun Xu, Andreas Haupt, Nancy Amato, Sanmi Koyejo.
Preprint, 2026.
Improving Single-round Active Adaptation: A Prediction Variability Perspective [ pdf ]
Xiaoyang Wang, Yibo Jacky Zhang, Olawale Elijah Salaudeen, Mingyuan Wu, Hongpeng Guo, Chaoyang He, Klara Nahrstedt, Sanmi Koyejo.
Transactions on Machine Learning Research (TMLR), 2025.
Exploring Learnability in Dynamical Stochastic Networks: A Field-Theoretic Approach [ pdf ]
Yibo Jacky Zhang, Sanmi Koyejo.
Symmetry and Geometry in Neural Representations (NeurReps) Workshop at NeurIPS 2025.
A Framework for Objective-Driven Dynamical Stochastic Fields [ pdf ]
Yibo Jacky Zhang, Sanmi Koyejo.
Preprint, 2025.
Aligning Compound AI Systems via System-level DPO [ pdf ]
Xiangwen Wang*, Yibo Jacky Zhang*, Zhoujie Ding, Katherine Tsai, Sanmi Koyejo.
Neural Information Processing Systems (NeurIPS), 2025.
Probing Human Visual Robustness with Neurally-Guided Deep Neural Networks [ pdf ]
Zhenan Shao, Linjian Ma, Yiqing Zhou, Yibo Jacky Zhang, Sanmi Koyejo, Bo Li, Diane M Beck.
Preprint, 2024.
Can Public Large Language Models Help Private Cross-device Federated Learning? [ pdf ]
Boxin Wang, Yibo Jacky Zhang, Yuan Cao, Bo Li, H. Brendan McMahan, Sewoong Oh, Zheng Xu, Manzil Zaheer.
NAACL 2024.
Principled Federated Domain Adaptation: Gradient Projection and Auto-Weighting [ pdf ]
Enyi Jiang*, Yibo Jacky Zhang*, Oluwasanmi Koyejo.
International Conference on Learning Representations (ICLR), 2024.
Batch Active Learning from the Perspective of Sparse Approximation [ pdf ] [ poster ]
Maohao Shen*, Bowen Jiang*, Jacky Y. Zhang*, Oluwasanmi Koyejo.
NeurIPS 2022 Workshop on Human in the Loop Learning.
Adversarially Robust Models may not Transfer Better: Sufficient Conditions for Domain Transferability from the View of Regularization [ pdf ] [ poster ] [ talk ]
Xiaojun Xu*, Jacky Y. Zhang*, Evelyn Ma, Danny Son, Oluwasanmi Koyejo, Bo Li
International Conference on Machine Learning (ICML), 2022.
Bayesian Coresets: Revisiting the Nonconvex Optimization Perspective
[ pdf ] [ poster ] [ short talk ] [ long talk ]
Jacky Y. Zhang, Rajiv Khanna, Anastasios Kyrillidis, Oluwasanmi Koyejo.
International Conference on Artificial Intelligence and Statistics (AISTATS), 2021. (Oral)
Uncovering the Connections Between Adversarial Transferability and Knowledge Transferability [ pdf ] [ poster ] [ talk ]
Kaizhao Liang*, Jacky Y. Zhang*, Boxin Wang, Zhuolin Yang, Oluwasanmi Koyejo, Bo Li
International Conference on Machine Learning (ICML), 2021.
Labeling Cost-Sensitive Batch Active Learning for Brain Tumor Segmentation
Maohao Shen, Jacky Y. Zhang, Leihao Chen, Weiman Yan, Neel Jani, Brad Sutton, Oluwasanmi Koyejo.
International Symposium on Biomedical Imaging (ISBI), 2021.
Robusta: Robust AutoML for Feature Selection via Reinforcement Learning [ pdf ]
Xiaoyang Wang, Bo Li, Yibo Zhang, Bhavya Kailkhura, Klara Nahrstedt.
AAAI 2021 Workshop Towards Robust, Secure and Efficient Machine Learning.
Learning Sparse Distributions using Iterative Hard Thresholding [ pdf ] [ poster ]
Jacky Y. Zhang, Rajiv Khanna, Anastasios Kyrillidis, Oluwasanmi Koyejo.
Neural Information Processing Systems (NeurIPS), 2019.
Maximizing Monotone DR-submodular Continuous Functions by Derivative-free Optimization [ pdf ]
Yibo Zhang, Chao Qian, Ke Tang.
Preprint: arXiv 1810.06833, 2018.
On Multiset Selection with Size Constraints [ pdf ]
Chao Qian, Yibo Zhang, Ke Tang, Xin Yao.
AAAI Conference on Artificial Intelligence (AAAI), 2018.
Contact yiboz@stanford.edu
Miscellaneous I like to ponder random things. For example: Would aliens also have their mouths near their brains? Will artificial and biological intelligence eventually converge? How much could I contribute to scientific progress if I were sent back in time 1000 years? And, most importantly, why are you still reading all this nonsense?
Photographer of Today: Matt Stuart Music of Today: A Love Song - EGO WRAPPIN' I will probably update these tomorrow almost surely with high probability.