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Lower bounds for finding stationary points I

2017/10/31 by Yair Carmon, Carmon, Yair, John C. Duchi +5 · 47 citations
Computer Science · Engineering · Mathematics · #Combinatorics #Complexity and Algorithms in Graphs #Computer science #Convex function #Discrete mathematics #Function (biology) #Geometry #Lipschitz continuity #Mathematical analysis #Mathematics #Nabla symbol #Oracle #Order (exchange) #Physics #Regular polygon #Regularization (linguistics) #Sparse and Compressive Sensing Techniques #Stationary point #Stochastic Gradient Optimization Techniques #Upper and lower bounds #math.OC

paper · pdf · doi:10.1007/s10107-019-01406-y

published in Mathematical Programming 184(1-2), 71-120 (Springer Science+Business Media)

openalex publication_date 2019/06/07 · arxiv created 2019/08/15 · arxiv updated 2019/08/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29

Abstract

We prove lower bounds on the complexity of finding ε-stationary points (points x such that ‖∇ f(x)‖ ≤ ε) of smooth, high-dimensional, and potentially non-convex functions f. We consider oracle-based complexity measures, where an algorithm is given access to the value and all derivatives of f at a query point x. We show that for any (potentially randomized) algorithm A, there exists a function f with Lipschitz pth order derivatives such that A requires at least ε-(p+1)/p queries to find an ε-stationary point. Our lower bounds are sharp to within constants, and they show that gradient descent, cubic-regularized Newton's method, and generalized pth order regularization are worst-case optimal within their natural function classes.

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