No dimension-free deterministic algorithm computes approximate stationarities of Lipschitzians

We consider the oracle complexity of computing an approximate stationary point of a Lipschitz function. When the function is smooth, it is well known that the simple deterministic gradient method has finite dimension-free oracle complexity. However, when the function can be nonsmooth, it is only rec...

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Vydáno v:Mathematical programming Ročník 208; číslo 1-2; s. 51 - 74
Hlavní autoři: Tian, Lai, So, Anthony Man-Cho
Médium: Journal Article
Jazyk:angličtina
Vydáno: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2024
Springer
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ISSN:0025-5610, 1436-4646
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Shrnutí:We consider the oracle complexity of computing an approximate stationary point of a Lipschitz function. When the function is smooth, it is well known that the simple deterministic gradient method has finite dimension-free oracle complexity. However, when the function can be nonsmooth, it is only recently that a randomized algorithm with finite dimension-free oracle complexity has been developed. In this paper, we show that no deterministic algorithm can do the same. Moreover, even without the dimension-free requirement, we show that any finite-time deterministic method cannot be general zero-respecting. In particular, this implies that a natural derandomization of the aforementioned randomized algorithm cannot have finite-time complexity. Our results reveal a fundamental hurdle in modern large-scale nonconvex nonsmooth optimization.
ISSN:0025-5610
1436-4646
DOI:10.1007/s10107-023-02031-6