arXiv Machine Learning

Large-Step Last-Iterate Convergence of Random-Reshuffling Stochastic Gradient Descent

arXiv Machine Learning
Aug 12

A lower bound for stepsize-based acceleration of gradient descent

arXiv:2608. 10418v1 Announce Type: cross Abstract: Recent work has shown that, for smooth convex optimization, plain gradient descent can be accelerated from its textbook convergence rate of $O(T^{-1})$ (where $T$ denotes the number of iterations) to $O\big(T^{-\log_2(1+\sqrt{2})}\big)$ using carefully designed stepsize schedules alone, without resorting to momentum or other algorithmic modifications.

By Jianhao Ma, Yuxin Chen
arXiv Machine Learning
5d ago

Generalization Guarantees of Randomized Block Coordinate Descent for Nonconvex Learning

The paper presents high‑probability generalization guarantees for Randomized Block Coordinate Descent (RBCD) when applied to nonconvex learning problems. It derives bounds on the gradients of both empirical and population risks under standard smoothness assumptions, and shows how polynomially decaying step sizes and early stopping can achieve optimal convergence rates for population gradients. In settings where the objective is gradient‑dominated, the authors provide functional suboptimality bounds that approach optimistic rates seen in convex or low‑noise scenarios, and they also establish dimension‑independent bounds for loss functions with a particular structure, extending applicability to high‑dimensional problems.

By Ruixi Hu, Liang Wu
arXiv Machine Learning
5d ago

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

High-Probability Convergence of SGD via Batched Updates

The paper introduces Batched SGD, a variant that groups online samples into epochs and performs a single update per epoch using a low‑variance gradient estimate. This batching approach allows a straightforward high‑probability analysis without restrictive assumptions or auxiliary sequences, yielding near‑optimal rates for both strongly convex and non‑convex objectives under standard smoothness and sub‑Gaussian noise conditions. The authors also extend the method to federated learning, providing the first high‑probability guarantees with logarithmic communication complexity, linear speedup in the number of agents, and robustness to data heterogeneity.

By Feng Zhu, Robert W. Heath Jr., Aritra Mitra
arXiv Machine Learning
Jul 1

Random Reshuffling Dominates Stochastic Gradient Descent

arXiv:2606. 32005v1 Announce Type: cross Abstract: Stochastic Gradient Descent ($\textsf{SGD}$) is one of the most classical optimization algorithms with favorable theoretical guarantees, yet the practical implementation of $\textsf{SGD}$ differs subtly from its well-known form and is often referred to as Shuffling Stochastic Gradient Descent ($\textsf{Shuffling SGD}$).

By Zijian Liu
arXiv Machine Learning
2d ago

A general recipe for data-adaptive anytime-valid envelopes for iterative algorithms

The paper introduces a general method for creating data‑adaptive, anytime‑valid envelopes that can be applied to a wide range of iterative stochastic algorithms. By reducing error analysis to a single requirement—time‑uniform concentration for predictably weighted sums of noise—the authors provide off‑the‑shelf boundary constructions using mixtures, stitching, and betting martingales. These envelopes are shown to be applicable to algorithms such as stochastic gradient descent, temporal difference learning, and Bures‑Wasserstein SGD, and they either match or improve upon existing bounds, with practical implementation details and numerical validation.

By Soham Bonnerjee, Aaditya Ramdas