A Linearly Involved Generalized Moreau Enhancement of <i>ℓ</i><sub>2,1</sub>-Norm with Application to Weighted Group Sparse Classification

This paper proposes a new group-sparsity-inducing regularizer to approximate <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mrow><mn>2</mn><mo>,</mo>&l...

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Autores principales: Yang Chen, Masao Yamagishi, Isao Yamada
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Publicado: MDPI AG 2021
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Acceso en línea:https://doaj.org/article/64f9e46ca8f4408a91b5946d0094eaf3
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spelling oai:doaj.org-article:64f9e46ca8f4408a91b5946d0094eaf32021-11-25T16:13:03ZA Linearly Involved Generalized Moreau Enhancement of <i>ℓ</i><sub>2,1</sub>-Norm with Application to Weighted Group Sparse Classification10.3390/a141103121999-4893https://doaj.org/article/64f9e46ca8f4408a91b5946d0094eaf32021-10-01T00:00:00Zhttps://www.mdpi.com/1999-4893/14/11/312https://doaj.org/toc/1999-4893This paper proposes a new group-sparsity-inducing regularizer to approximate <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mrow><mn>2</mn><mo>,</mo><mn>0</mn></mrow></msub></semantics></math></inline-formula> pseudo-norm. The regularizer is nonconvex, which can be seen as a linearly involved generalized Moreau enhancement of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mrow><mn>2</mn><mo>,</mo><mn>1</mn></mrow></msub></semantics></math></inline-formula>-norm. Moreover, the overall convexity of the corresponding group-sparsity-regularized least squares problem can be achieved. The model can handle general group configurations such as weighted group sparse problems, and can be solved through a proximal splitting algorithm. Among the applications, considering that the bias of convex regularizer may lead to incorrect classification results especially for unbalanced training sets, we apply the proposed model to the (weighted) group sparse classification problem. The proposed classifier can use the label, similarity and locality information of samples. It also suppresses the bias of convex regularizer-based classifiers. Experimental results demonstrate that the proposed classifier improves the performance of convex <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mrow><mn>2</mn><mo>,</mo><mn>1</mn></mrow></msub></semantics></math></inline-formula> regularizer-based methods, especially when the training data set is unbalanced. This paper enhances the potential applicability and effectiveness of using nonconvex regularizers in the frame of convex optimization.Yang ChenMasao YamagishiIsao YamadaMDPI AGarticleconvex optimizationproximal splitting algorithmgeneralized Moreau enhancementgroup sparsityweighted <i>ℓ</i><sub>2,1</sub>-normsparse representation-based classificationIndustrial engineering. Management engineeringT55.4-60.8Electronic computers. Computer scienceQA75.5-76.95ENAlgorithms, Vol 14, Iss 312, p 312 (2021)
institution DOAJ
collection DOAJ
language EN
topic convex optimization
proximal splitting algorithm
generalized Moreau enhancement
group sparsity
weighted <i>ℓ</i><sub>2,1</sub>-norm
sparse representation-based classification
Industrial engineering. Management engineering
T55.4-60.8
Electronic computers. Computer science
QA75.5-76.95
spellingShingle convex optimization
proximal splitting algorithm
generalized Moreau enhancement
group sparsity
weighted <i>ℓ</i><sub>2,1</sub>-norm
sparse representation-based classification
Industrial engineering. Management engineering
T55.4-60.8
Electronic computers. Computer science
QA75.5-76.95
Yang Chen
Masao Yamagishi
Isao Yamada
A Linearly Involved Generalized Moreau Enhancement of <i>ℓ</i><sub>2,1</sub>-Norm with Application to Weighted Group Sparse Classification
description This paper proposes a new group-sparsity-inducing regularizer to approximate <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mrow><mn>2</mn><mo>,</mo><mn>0</mn></mrow></msub></semantics></math></inline-formula> pseudo-norm. The regularizer is nonconvex, which can be seen as a linearly involved generalized Moreau enhancement of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mrow><mn>2</mn><mo>,</mo><mn>1</mn></mrow></msub></semantics></math></inline-formula>-norm. Moreover, the overall convexity of the corresponding group-sparsity-regularized least squares problem can be achieved. The model can handle general group configurations such as weighted group sparse problems, and can be solved through a proximal splitting algorithm. Among the applications, considering that the bias of convex regularizer may lead to incorrect classification results especially for unbalanced training sets, we apply the proposed model to the (weighted) group sparse classification problem. The proposed classifier can use the label, similarity and locality information of samples. It also suppresses the bias of convex regularizer-based classifiers. Experimental results demonstrate that the proposed classifier improves the performance of convex <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mrow><mn>2</mn><mo>,</mo><mn>1</mn></mrow></msub></semantics></math></inline-formula> regularizer-based methods, especially when the training data set is unbalanced. This paper enhances the potential applicability and effectiveness of using nonconvex regularizers in the frame of convex optimization.
format article
author Yang Chen
Masao Yamagishi
Isao Yamada
author_facet Yang Chen
Masao Yamagishi
Isao Yamada
author_sort Yang Chen
title A Linearly Involved Generalized Moreau Enhancement of <i>ℓ</i><sub>2,1</sub>-Norm with Application to Weighted Group Sparse Classification
title_short A Linearly Involved Generalized Moreau Enhancement of <i>ℓ</i><sub>2,1</sub>-Norm with Application to Weighted Group Sparse Classification
title_full A Linearly Involved Generalized Moreau Enhancement of <i>ℓ</i><sub>2,1</sub>-Norm with Application to Weighted Group Sparse Classification
title_fullStr A Linearly Involved Generalized Moreau Enhancement of <i>ℓ</i><sub>2,1</sub>-Norm with Application to Weighted Group Sparse Classification
title_full_unstemmed A Linearly Involved Generalized Moreau Enhancement of <i>ℓ</i><sub>2,1</sub>-Norm with Application to Weighted Group Sparse Classification
title_sort linearly involved generalized moreau enhancement of <i>ℓ</i><sub>2,1</sub>-norm with application to weighted group sparse classification
publisher MDPI AG
publishDate 2021
url https://doaj.org/article/64f9e46ca8f4408a91b5946d0094eaf3
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AT masaoyamagishi alinearlyinvolvedgeneralizedmoreauenhancementofilisub21subnormwithapplicationtoweightedgroupsparseclassification
AT isaoyamada alinearlyinvolvedgeneralizedmoreauenhancementofilisub21subnormwithapplicationtoweightedgroupsparseclassification
AT yangchen linearlyinvolvedgeneralizedmoreauenhancementofilisub21subnormwithapplicationtoweightedgroupsparseclassification
AT masaoyamagishi linearlyinvolvedgeneralizedmoreauenhancementofilisub21subnormwithapplicationtoweightedgroupsparseclassification
AT isaoyamada linearlyinvolvedgeneralizedmoreauenhancementofilisub21subnormwithapplicationtoweightedgroupsparseclassification
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