Deep ReLU networks and high-order finite element methods II: Chebyshev emulation

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Autori principali: Opschoor, Joost A. A., Schwab, Christoph
Natura: Preprint
Pubblicazione: 2023
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author Opschoor, Joost A. A.
Schwab, Christoph
author_facet Opschoor, Joost A. A.
Schwab, Christoph
contents We show expression rates and stability in Sobolev norms of deep feedforward ReLU neural networks (NNs) in terms of the number of parameters defining the NN for continuous, piecewise polynomial functions, on arbitrary, finite partitions $\mathcal{T}$ of a bounded interval $(a,b)$. Novel constructions of ReLU NN surrogates encoding function approximations in terms of Chebyshev polynomial expansion coefficients are developed which require fewer neurons than previous constructions. Chebyshev coefficients can be computed easily from the values of the function in the Clenshaw--Curtis points using the inverse fast Fourier transform. Bounds on expression rates and stability are obtained that are superior to those of constructions based on ReLU NN emulations of monomials as considered in [Opschoor, Petersen and Schwab, 2020] and [Montanelli, Yang and Du, 2021]. All emulation bounds are explicit in terms of the (arbitrary) partition of the interval, the target emulation accuracy and the polynomial degree in each element of the partition. ReLU NN emulation error estimates are provided for various classes of functions and norms, commonly encountered in numerical analysis. In particular, we show exponential ReLU emulation rate bounds for analytic functions with point singularities and develop an interface between Chebfun approximations and constructive ReLU NN emulations.
format Preprint
id arxiv_https___arxiv_org_abs_2310_07261
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Deep ReLU networks and high-order finite element methods II: Chebyshev emulation
Opschoor, Joost A. A.
Schwab, Christoph
Numerical Analysis
Machine Learning
65N30, 41A05, 41A10, 41A25, 41A50
We show expression rates and stability in Sobolev norms of deep feedforward ReLU neural networks (NNs) in terms of the number of parameters defining the NN for continuous, piecewise polynomial functions, on arbitrary, finite partitions $\mathcal{T}$ of a bounded interval $(a,b)$. Novel constructions of ReLU NN surrogates encoding function approximations in terms of Chebyshev polynomial expansion coefficients are developed which require fewer neurons than previous constructions. Chebyshev coefficients can be computed easily from the values of the function in the Clenshaw--Curtis points using the inverse fast Fourier transform. Bounds on expression rates and stability are obtained that are superior to those of constructions based on ReLU NN emulations of monomials as considered in [Opschoor, Petersen and Schwab, 2020] and [Montanelli, Yang and Du, 2021]. All emulation bounds are explicit in terms of the (arbitrary) partition of the interval, the target emulation accuracy and the polynomial degree in each element of the partition. ReLU NN emulation error estimates are provided for various classes of functions and norms, commonly encountered in numerical analysis. In particular, we show exponential ReLU emulation rate bounds for analytic functions with point singularities and develop an interface between Chebfun approximations and constructive ReLU NN emulations.
title Deep ReLU networks and high-order finite element methods II: Chebyshev emulation
topic Numerical Analysis
Machine Learning
65N30, 41A05, 41A10, 41A25, 41A50
url https://arxiv.org/abs/2310.07261