arXiv Machine Learning

Variance Reduction with Delayed Feedback for Non-Convex Optimization

The paper investigates variance reduction techniques for non‑convex optimization when gradient evaluations are delayed. It introduces an ordered recursive momentum estimator whose oracle complexity depends on smoothness, variance, and delay, and provides bounds for both stochastic and finite‑sum settings. An asynchronous snapshot variant is also proposed, allowing updates during full‑gradient computations under a completion‑time bound.

arXiv Machine Learning
Sep 17

Revisiting Distributed Sign-Based Variance Reduction

The paper addresses bias introduced by aggregating local signs in distributed sign-based variance reduction methods, which hampers optimal convergence rates. By proposing an unbiased compression of recursive gradient increments to track the global gradient at the server, the authors achieve optimal convergence rates for both nonconvex stochastic and finite-sum optimization. They provide specific rate bounds for α-norms and demonstrate matching sample complexities to centralized settings for finite-sum problems.

By Wei Jiang, Zechao Li, Lijun Zhang
arXiv Machine Learning
Oct 3

Convergence Analysis of STORM Under Different Geometries

arXiv:2610. 01599v1 Announce Type: cross Abstract: Stochastic recursive momentum (STORM) achieves fast convergence for nonconvex optimization via the variance reduction effect, but existing analyses rely on the strong average smoothness assumption.

By Wei Jiang, Yibo Wang, Wenhao Yang, Rui Yan, Lijun Zhang, Zechao Li
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