Optimal Stochastic Non-smooth Non-convex Optimization through Online-to-Non-convex Conversion

Fuente: arXiv
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Hauptverfasser: Cutkosky, Ashok, Mehta, Harsh, Orabona, Francesco
Format: Preprint
Veröffentlicht: 2023
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author Cutkosky, Ashok
Mehta, Harsh
Orabona, Francesco
author_facet Cutkosky, Ashok
Mehta, Harsh
Orabona, Francesco
contents We present new algorithms for optimizing non-smooth, non-convex stochastic objectives based on a novel analysis technique. This improves the current best-known complexity for finding a $(δ,ε)$-stationary point from $O(ε^{-4}δ^{-1})$ stochastic gradient queries to $O(ε^{-3}δ^{-1})$, which we also show to be optimal. Our primary technique is a reduction from non-smooth non-convex optimization to online learning, after which our results follow from standard regret bounds in online learning. For deterministic and second-order smooth objectives, applying more advanced optimistic online learning techniques enables a new complexity of $O(ε^{-1.5}δ^{-0.5})$. Our techniques also recover all optimal or best-known results for finding $ε$ stationary points of smooth or second-order smooth objectives in both stochastic and deterministic settings.
format Preprint
id arxiv_https___arxiv_org_abs_2302_03775
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Optimal Stochastic Non-smooth Non-convex Optimization through Online-to-Non-convex Conversion
Cutkosky, Ashok
Mehta, Harsh
Orabona, Francesco
Machine Learning
Optimization and Control
We present new algorithms for optimizing non-smooth, non-convex stochastic objectives based on a novel analysis technique. This improves the current best-known complexity for finding a $(δ,ε)$-stationary point from $O(ε^{-4}δ^{-1})$ stochastic gradient queries to $O(ε^{-3}δ^{-1})$, which we also show to be optimal. Our primary technique is a reduction from non-smooth non-convex optimization to online learning, after which our results follow from standard regret bounds in online learning. For deterministic and second-order smooth objectives, applying more advanced optimistic online learning techniques enables a new complexity of $O(ε^{-1.5}δ^{-0.5})$. Our techniques also recover all optimal or best-known results for finding $ε$ stationary points of smooth or second-order smooth objectives in both stochastic and deterministic settings.
title Optimal Stochastic Non-smooth Non-convex Optimization through Online-to-Non-convex Conversion
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2302.03775