Universal Concavity-Aware Descent Rate for Optimizers

ICLR 2025 Conference Submission4343 Authors

25 Sept 2024 (modified: 13 Oct 2024)ICLR 2025 Conference SubmissionEveryoneRevisionsBibTeXCC BY 4.0
Keywords: nonconvex optimization, optimization, convergence rate, objective function sub-optimality, objective sub-optimality, quasi newton optimization, numerical methods, lipschitz adaptive, eigenspace lipschitz
TL;DR: We prove a function suboptimality gap convergence rate for general quasi-newton optimization algorithms and nonconvex functions, and develop a tool for optimizer hyperparameter selection in neural network training.
Abstract: Many machine learning problems involve a challenging task of calibrating parameters in a computational model to fit the training data; this task is especially challenging for non-convex problems. Many optimization algorithms have been proposed to assist in calibrating these parameters, each with its respective advantages in different scenarios, but it is often difficult to determine the scenarios for which an algorithm is best suited. To contend with this challenge, much work has been done on proving the rate at which these optimizers converge to their final solution, however the wide variety of such convergence rate bounds, each with their own different assumptions, convergence metrics, tightnesses, and parameters (which may or may not be known to the practitioner) make comparing these convergence rates difficult. To help with this problem, we present a minmax-optimal algorithm and, by comparison to it, give a single descent bound which is applicable to a very wide family of optimizers, tasks, and data (including all of the most prevalent ones), which also puts special emphasis on being tight even in parameter subspaces in which the cost function is concave.
Primary Area: optimization
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Submission Number: 4343
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