arXiv Computer Vision

Adaptive Extrapolated Proximal Gradient Methods with Variance Reduction for Composite Nonconvex Finite-Sum Minimization

arXiv Machine Learning
Aug 10

A proximal subgradient method for nonconvex stochastic optimization under the Kurdyka-{\L}ojasiewicz condition

arXiv:2608. 05460v1 Announce Type: cross Abstract: This work introduces a proximal stochastic subgradient method for minimizing the sum of an expected cost, whose integrand is potentially nonsmooth and nonconvex, and a lower semicontinuous, prox-bounded function.

By Felipe Atenas, Alejandro Jofr\'e, Pedro P\'erez-Aros, David Torregrosa-Bel\'en
arXiv Machine Learning
Oct 21

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.

By Wei Jiang, Dingzhi Yu, Zechao Li
arXiv Machine Learning
Aug 27

Adaptivity via a Parallel Architecture for Stochastic Gradient Methods

The paper introduces a parallel architecture for stochastic gradient methods that adaptively selects the number of iterations. An algorithm A(x₀, y) takes an initial point and a step limit y, and p processors search for an appropriate iteration count T using a prescribed function h. The framework guarantees a (p, αₚ)-approximation, meaning for any T ≥ T₀ there exists a processor and stage where the cumulative iterations lie within a factor αₚ of T, and the authors prove tight lower bounds for αₚ while presenting simple arithmetic stochastic gradient methods that use only divisions by powers of two.

By Bin Fu
arXiv Machine Learning
Sep 23

Polyak-Type Extragradient Methods for Monotone Root-Finding Problems

The paper investigates Polyak-type step-size strategies for extragradient methods applied to deterministic and stochastic monotone root-finding problems. It shows that the projection-based correction in deterministic extragradient can be derived by minimizing an upper bound on the distance to a solution, mirroring classical Polyak step-size construction. The authors provide a unified deterministic analysis that does not require global Lipschitz continuity, achieving sublinear convergence under H"older or “(L0, L1)-Lipschitz” conditions and linear convergence with strong monotonicity, and extend the approach to stochastic settings with both direct and decreasing step-size variants.

By TaeHo Yoon, Sayantan Choudhury, Ezra Greenberg, Nicolas Loizou