Smooth Function Approximation by Deep Neural Networks with General Activation Functions

There has been a growing interest in expressivity of deep neural networks. However, most of the existing work about this topic focuses only on the specific activation function such as ReLU or sigmoid. In this paper, we investigate the approximation ability of deep neural networks with a broad class...

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Main Authors: Ilsang Ohn, Yongdai Kim
Format: Article
Language:English
Published: MDPI AG 2019-06-01
Series:Entropy
Subjects:
Online Access:https://www.mdpi.com/1099-4300/21/7/627
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author Ilsang Ohn
Yongdai Kim
author_facet Ilsang Ohn
Yongdai Kim
author_sort Ilsang Ohn
collection DOAJ
description There has been a growing interest in expressivity of deep neural networks. However, most of the existing work about this topic focuses only on the specific activation function such as ReLU or sigmoid. In this paper, we investigate the approximation ability of deep neural networks with a broad class of activation functions. This class of activation functions includes most of frequently used activation functions. We derive the required depth, width and sparsity of a deep neural network to approximate any Hölder smooth function upto a given approximation error for the large class of activation functions. Based on our approximation error analysis, we derive the minimax optimality of the deep neural network estimators with the general activation functions in both regression and classification problems.
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spelling doaj.art-b679be97d72f46f9a1a7bf79a638b1552022-12-22T04:25:15ZengMDPI AGEntropy1099-43002019-06-0121762710.3390/e21070627e21070627Smooth Function Approximation by Deep Neural Networks with General Activation FunctionsIlsang Ohn0Yongdai Kim1Department of Statistics, Seoul National University, Seoul 08826, KoreaDepartment of Statistics, Seoul National University, Seoul 08826, KoreaThere has been a growing interest in expressivity of deep neural networks. However, most of the existing work about this topic focuses only on the specific activation function such as ReLU or sigmoid. In this paper, we investigate the approximation ability of deep neural networks with a broad class of activation functions. This class of activation functions includes most of frequently used activation functions. We derive the required depth, width and sparsity of a deep neural network to approximate any Hölder smooth function upto a given approximation error for the large class of activation functions. Based on our approximation error analysis, we derive the minimax optimality of the deep neural network estimators with the general activation functions in both regression and classification problems.https://www.mdpi.com/1099-4300/21/7/627function approximationdeep neural networksactivation functionsHölder continuityconvergence rates
spellingShingle Ilsang Ohn
Yongdai Kim
Smooth Function Approximation by Deep Neural Networks with General Activation Functions
Entropy
function approximation
deep neural networks
activation functions
Hölder continuity
convergence rates
title Smooth Function Approximation by Deep Neural Networks with General Activation Functions
title_full Smooth Function Approximation by Deep Neural Networks with General Activation Functions
title_fullStr Smooth Function Approximation by Deep Neural Networks with General Activation Functions
title_full_unstemmed Smooth Function Approximation by Deep Neural Networks with General Activation Functions
title_short Smooth Function Approximation by Deep Neural Networks with General Activation Functions
title_sort smooth function approximation by deep neural networks with general activation functions
topic function approximation
deep neural networks
activation functions
Hölder continuity
convergence rates
url https://www.mdpi.com/1099-4300/21/7/627
work_keys_str_mv AT ilsangohn smoothfunctionapproximationbydeepneuralnetworkswithgeneralactivationfunctions
AT yongdaikim smoothfunctionapproximationbydeepneuralnetworkswithgeneralactivationfunctions