arXiv Machine Learning

Last-Iterate Convergence of Stochastic Gradient Methods for Unbounded Problems

The paper investigates last‑iterate convergence for proximal and projected stochastic gradient methods in settings without bounded domain or bounded variance assumptions, using black‑box variational inference as an example. It establishes a near‑optimal anytime rate of ×(1/√T) for the last iterate under two relaxed assumptions, and shows that when the horizon T is known, the logarithmic factor can be removed to achieve the optimal ×(1/√T) rate, matching results that previously required bounded variance or domain constraints.

arXiv Machine Learning
Jul 2

Towards Weaker Variance Assumptions for Stochastic Optimization

arXiv:2504. 09951v2 Announce Type: replace-cross Abstract: We revisit a classical assumption for analyzing stochastic gradient algorithms where the squared norm of the stochastic subgradient (or the variance for smooth problems) is allowed to grow as fast as the squared norm of the optimization variable.

By Ahmet Alacaoglu, Yura Malitsky, Stephen J. Wright
arXiv Machine Learning
Oct 16

On the Last-Iterate Convergence of Clipped Gradient Methods

The paper establishes the first optimal last‑iterate convergence rates, in high probability, for Clipped‑SGD when the gradient noise is heavy‑tailed. It addresses the gap left by earlier results that required strong noise assumptions, such as exponentially decaying tails. By proving these rates, the authors provide theoretical support for the practical effectiveness of gradient clipping in stochastic convex optimization.

By Zijian Liu
arXiv Machine Learning
Sep 14

Almost Sure Convergence Analysis of Stochastic Gradient Methods with Clipping and Additive Noise

The paper proves that stochastic gradient descent with gradient clipping and additive Gaussian noise (SGD‑CN) converges almost surely under smoothness and bounded noise assumptions, given standard decaying step sizes. The analysis extends to momentum variants such as the stochastic heavy ball and Nesterov's accelerated gradient, showing that careful energy constructions yield similar guarantees. These results provide stronger theoretical foundations for understanding the pathwise behaviour of clipped stochastic gradient methods in both convex and nonconvex regimes.

By Amartya Mukherjee, Jun Liu