Constrained Online Convex Optimization with Polyak Feasibility Steps

Fuente: arXiv
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Autores principales: Hutchinson, Spencer, Alizadeh, Mahnoosh
Formato: Preprint
Publicado: 2025
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author Hutchinson, Spencer
Alizadeh, Mahnoosh
author_facet Hutchinson, Spencer
Alizadeh, Mahnoosh
contents In this work, we study online convex optimization with a fixed constraint function $g : \mathbb{R}^d \rightarrow \mathbb{R}$. Prior work on this problem has shown $O(\sqrt{T})$ regret and cumulative constraint satisfaction $\sum_{t=1}^{T} g(x_t) \leq 0$, while only accessing the constraint value and subgradient at the played actions $g(x_t), \partial g(x_t)$. Using the same constraint information, we show a stronger guarantee of anytime constraint satisfaction $g(x_t) \leq 0 \ \forall t \in [T]$, and matching $O(\sqrt{T})$ regret guarantees. These contributions are thanks to our approach of using Polyak feasibility steps to ensure constraint satisfaction, without sacrificing regret. Specifically, after each step of online gradient descent, our algorithm applies a subgradient descent step on the constraint function where the step-size is chosen according to the celebrated Polyak step-size. We further validate this approach with numerical experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2502_13112
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Constrained Online Convex Optimization with Polyak Feasibility Steps
Hutchinson, Spencer
Alizadeh, Mahnoosh
Machine Learning
Optimization and Control
In this work, we study online convex optimization with a fixed constraint function $g : \mathbb{R}^d \rightarrow \mathbb{R}$. Prior work on this problem has shown $O(\sqrt{T})$ regret and cumulative constraint satisfaction $\sum_{t=1}^{T} g(x_t) \leq 0$, while only accessing the constraint value and subgradient at the played actions $g(x_t), \partial g(x_t)$. Using the same constraint information, we show a stronger guarantee of anytime constraint satisfaction $g(x_t) \leq 0 \ \forall t \in [T]$, and matching $O(\sqrt{T})$ regret guarantees. These contributions are thanks to our approach of using Polyak feasibility steps to ensure constraint satisfaction, without sacrificing regret. Specifically, after each step of online gradient descent, our algorithm applies a subgradient descent step on the constraint function where the step-size is chosen according to the celebrated Polyak step-size. We further validate this approach with numerical experiments.
title Constrained Online Convex Optimization with Polyak Feasibility Steps
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2502.13112