Abstract
While it is well-known that nonlinear methods of approximation can often perform dramatically better than linear methods, there are still questions on how to measure the optimal performance possible for such methods. This paper studies nonlinear methods of approximation that are compatible with numerical implementation in that they are required to be numerically stable. A measure of optimal performance, called stable manifold widths, for approximating a model class K in a Banach space X by stable manifold methods is introduced. Fundamental inequalities between these stable manifold widths and the entropy of K are established. The effects of requiring stability in the settings of deep learning and compressed sensing are discussed.
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The authors thank Professor Giles Godefroy for insightful discussions on the results of this paper.
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Communicated by Pencho Petrushev.
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This research was supported by the NSF Grant DMS 1817603 (RD-GP) and the ONR Contract N00014-17-1-2908 (RD). P. W. was supported by National Science Centre, Polish Grant UMO-2016/21/B/ST1/00241. A portion of this research was completed when the first three authors were visiting the Isaac Newton InstituteTripods Grant CCF-1934904 (RD-GP); ONR Contract N00014-20-1-2787 (RD-GP).
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Cohen, A., DeVore, R., Petrova, G. et al. Optimal Stable Nonlinear Approximation. Found Comput Math 22, 607–648 (2022). https://doi.org/10.1007/s10208-021-09494-z
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DOI: https://doi.org/10.1007/s10208-021-09494-z
Keywords
- Nonlinear approximation
- n-widths
- Entropy numbers
- Bounded approximation property
- Stable approximation methods