Tight Lower Bounds under Asymmetric High-Order Hölder Smoothness and Uniform Convexity

Fuente: arXiv
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Auteurs principaux: Bai, Cedar Site, Bullins, Brian
Format: Preprint
Publié: 2024
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author Bai, Cedar Site
Bullins, Brian
author_facet Bai, Cedar Site
Bullins, Brian
contents In this paper, we provide tight lower bounds for the oracle complexity of minimizing high-order Hölder smooth and uniformly convex functions. Specifically, for a function whose $p^{th}$-order derivatives are Hölder continuous with degree $ν$ and parameter $H$, and that is uniformly convex with degree $q$ and parameter $σ$, we focus on two asymmetric cases: (1) $q > p + ν$, and (2) $q < p+ν$. Given up to $p^{th}$-order oracle access, we establish worst-case oracle complexities of $Ω\left( \left( \frac{H}σ\right)^\frac{2}{3(p+ν)-2}\left( \fracσε\right)^\frac{2(q-p-ν)}{q(3(p+ν)-2)}\right)$ in the first case with an $\ell_\infty$-ball-truncated-Gaussian smoothed hard function and $Ω\left(\left(\frac{H}σ\right)^\frac{2}{3(p+ν)-2}+ \log\log\left(\left(\frac{σ^{p+ν}}{H^q}\right)^\frac{1}{p+ν-q}\frac{1}ε\right)\right)$ in the second case, for reaching an $ε$-approximate solution in terms of the optimality gap. Our analysis generalizes previous lower bounds for functions under first- and second-order smoothness as well as those for uniformly convex functions, and furthermore our results match the corresponding upper bounds in this general setting.
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id arxiv_https___arxiv_org_abs_2409_10773
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Tight Lower Bounds under Asymmetric High-Order Hölder Smoothness and Uniform Convexity
Bai, Cedar Site
Bullins, Brian
Optimization and Control
Machine Learning
In this paper, we provide tight lower bounds for the oracle complexity of minimizing high-order Hölder smooth and uniformly convex functions. Specifically, for a function whose $p^{th}$-order derivatives are Hölder continuous with degree $ν$ and parameter $H$, and that is uniformly convex with degree $q$ and parameter $σ$, we focus on two asymmetric cases: (1) $q > p + ν$, and (2) $q < p+ν$. Given up to $p^{th}$-order oracle access, we establish worst-case oracle complexities of $Ω\left( \left( \frac{H}σ\right)^\frac{2}{3(p+ν)-2}\left( \fracσε\right)^\frac{2(q-p-ν)}{q(3(p+ν)-2)}\right)$ in the first case with an $\ell_\infty$-ball-truncated-Gaussian smoothed hard function and $Ω\left(\left(\frac{H}σ\right)^\frac{2}{3(p+ν)-2}+ \log\log\left(\left(\frac{σ^{p+ν}}{H^q}\right)^\frac{1}{p+ν-q}\frac{1}ε\right)\right)$ in the second case, for reaching an $ε$-approximate solution in terms of the optimality gap. Our analysis generalizes previous lower bounds for functions under first- and second-order smoothness as well as those for uniformly convex functions, and furthermore our results match the corresponding upper bounds in this general setting.
title Tight Lower Bounds under Asymmetric High-Order Hölder Smoothness and Uniform Convexity
topic Optimization and Control
Machine Learning
url https://arxiv.org/abs/2409.10773