An optimal first-order method for smooth and strongly convex composite optimization and its stationary limit

Fuente: arXiv
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Main Authors: Upadhyaya, Manu, Thomsen, Daniel Berg, Dieuleveut, Aymeric, Taylor, Adrien B.
Format: Preprint
Published: 2026
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author Upadhyaya, Manu
Thomsen, Daniel Berg
Dieuleveut, Aymeric
Taylor, Adrien B.
author_facet Upadhyaya, Manu
Thomsen, Daniel Berg
Dieuleveut, Aymeric
Taylor, Adrien B.
contents We introduce Prox-ITEM, an optimal proximal gradient method for minimizing $f+g$, where $f$ is smooth and strongly convex, and $g$ is convex, proper, and lower semicontinuous. In the smooth case $g=0$, Prox-ITEM reduces to the information-theoretic exact method (ITEM). We prove an exact distance-to-solution bound for Prox-ITEM with the same distance-convergence rate as ITEM, and show that this rate is minimax optimal among span-based first-order methods using the same number of gradient-oracle calls for $f$ and an arbitrary number of proximal-oracle calls for $g$. We also identify the stationary limit of Prox-ITEM, denoted Prox-TMM, which gives a proximal extension of the triple momentum method (TMM) to the composite setting and achieves the corresponding TMM distance-convergence rate.
format Preprint
id arxiv_https___arxiv_org_abs_2605_22929
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle An optimal first-order method for smooth and strongly convex composite optimization and its stationary limit
Upadhyaya, Manu
Thomsen, Daniel Berg
Dieuleveut, Aymeric
Taylor, Adrien B.
Optimization and Control
We introduce Prox-ITEM, an optimal proximal gradient method for minimizing $f+g$, where $f$ is smooth and strongly convex, and $g$ is convex, proper, and lower semicontinuous. In the smooth case $g=0$, Prox-ITEM reduces to the information-theoretic exact method (ITEM). We prove an exact distance-to-solution bound for Prox-ITEM with the same distance-convergence rate as ITEM, and show that this rate is minimax optimal among span-based first-order methods using the same number of gradient-oracle calls for $f$ and an arbitrary number of proximal-oracle calls for $g$. We also identify the stationary limit of Prox-ITEM, denoted Prox-TMM, which gives a proximal extension of the triple momentum method (TMM) to the composite setting and achieves the corresponding TMM distance-convergence rate.
title An optimal first-order method for smooth and strongly convex composite optimization and its stationary limit
topic Optimization and Control
url https://arxiv.org/abs/2605.22929