Inference for Stochastic Gradient Descent: Beyond Finite Variance.
Time: 2026-11-04
Published By: Congcong Zhao
Speaker(s): Prof. Wenhao Yang (Peking University)
Time: 10:00-11:30 November 11, 2026
Venue: Room 9, Quan Zhai, BICMR
Abstract: Stochastic gradient descent (SGD) plays a foundational role in large-scale machine learning, yet its behavior in realistic training environments often departs from what classical finite-variance theory assumes. Empirical studies indicate that gradient noise can be highly irregular, with occasional large fluctuations and non-Gaussian patterns. Such behavior plays a critical role in shaping optimization dynamics and model calibration. In this talk, I will discuss an approach to inference for SGD that goes beyond the traditional finite-variance paradigm. I will first describe how SGD behaves asymptotically under realistic noise conditions, emphasizing the key differences from the standard finite-variance viewpoint. I will then introduce a general methodology for uncertainty quantification and confidence-region construction for SGD-based solutions, applicable even when the underlying gradient noise lacks finite variance. This approach provides practical tools for assessing the reliability of stochastic optimization in modern learning systems. I will conclude with a discussion of practical implications and several open directions connecting optimization behavior with inference procedures.
