Lower bounds for non-convex stochastic optimization
We lower bound the complexity of finding ϵ -stationary points (with gradient norm at most ϵ ) using stochastic first-order methods. In a well-studied model where algorithms access smooth, potentially non-convex functions through queries to an unbiased stochastic gradient oracle with bounded variance...
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| Veröffentlicht in: | Mathematical programming Jg. 199; H. 1-2; S. 165 - 214 |
|---|---|
| Hauptverfasser: | , , , , , |
| Format: | Journal Article |
| Sprache: | Englisch |
| Veröffentlicht: |
Berlin/Heidelberg
Springer Berlin Heidelberg
01.05.2023
Springer |
| Schlagworte: | |
| ISSN: | 0025-5610, 1436-4646 |
| Online-Zugang: | Volltext |
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| Zusammenfassung: | We lower bound the complexity of finding
ϵ
-stationary points (with gradient norm at most
ϵ
) using stochastic first-order methods. In a well-studied model where algorithms access smooth, potentially non-convex functions through queries to an unbiased stochastic gradient oracle with bounded variance, we prove that (in the worst case) any algorithm requires at least
ϵ
-
4
queries to find an
ϵ
-stationary point. The lower bound is tight, and establishes that stochastic gradient descent is minimax optimal in this model. In a more restrictive model where the noisy gradient estimates satisfy a mean-squared smoothness property, we prove a lower bound of
ϵ
-
3
queries, establishing the optimality of recently proposed variance reduction techniques. |
|---|---|
| ISSN: | 0025-5610 1436-4646 |
| DOI: | 10.1007/s10107-022-01822-7 |