School of CSE Seminar Series: Yuejie Chi

Speaker: Carnegie Mellon University Professor Yuejie Chi
Date and Time: April 5, 2:00-3:00 p.m.
Location: Coda 114
Host: Bo Dai

Title: Solving Inverse Problems with Generative Priors: From Low-rank to Diffusion Models

Abstract: Generative priors are effective countermeasures to combat the curse of dimensionality, and enable efficient learning and inversion that otherwise are ill-posed, in data science. This talk begins with the classical low-rank prior, and introduces scaled gradient descent (ScaledGD), a simple iterative approach to directly recover the low-rank factors for a wide range of matrix and tensor estimation tasks. ScaledGD provably converges linearly at a constant rate independent of the condition number at near-optimal sample complexities, while maintaining the low per-iteration cost of vanilla gradient descent, even when the rank is overspecified and the initialization is random. Going beyond low rank, the talk discusses score-based diffusion models as an expressive data prior in inverse problems, and introduces a plug-and-play method (Diffusion PnP) that alternatively calls two samplers, a denoising diffusion sampler based solely on the unconditional score functions of data, and a proximal consistency sampler solely based on the forward model. Performance guarantees and numerical examples will be demonstrated to illustrate the promise.

Bio: Dr. Yuejie Chi is the Sense of Wonder Group Endowed Professor of Electrical and Computer Engineering in AI Systems at Carnegie Mellon University, with courtesy appointments in the Machine Learning department and CyLab. She received her Ph.D. and M.A. from Princeton University, and B. Eng. (Hon.) from Tsinghua University, all in Electrical Engineering. Her research interests lie in the theoretical and algorithmic foundations of data science, signal processing, machine learning and inverse problems, with applications in sensing, imaging, decision making, and AI systems. Among others, Dr. Chi received the Presidential Early Career Award for Scientists and Engineers (PECASE), SIAM Activity Group on Imaging Science Best Paper Prize, IEEE Signal Processing Society Young Author Best Paper Award, and the inaugural IEEE Signal Processing Society Early Career Technical Achievement Award for contributions to high-dimensional structured signal processing. She is an IEEE Fellow (Class of 2023) for contributions to statistical signal processing with low-dimensional structures.