Quasi-Irreducibility of Nonnegative Biquadratic Tensors

While the adjacency tensor of a bipartite 2-graph is a nonnegative biquadratic tensor, it is inherently reducible. To address this limitation, we introduce the concept of quasi-irreducibility in this paper. The adjacency tensor of a bipartite 2-graph is quasi-irreducible if that bipartite 2-graph is...

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Main Authors: Liqun Qi, Chunfeng Cui, Yi Xu
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Mathematics
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Online Access:https://www.mdpi.com/2227-7390/13/13/2066
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author Liqun Qi
Chunfeng Cui
Yi Xu
author_facet Liqun Qi
Chunfeng Cui
Yi Xu
author_sort Liqun Qi
collection DOAJ
description While the adjacency tensor of a bipartite 2-graph is a nonnegative biquadratic tensor, it is inherently reducible. To address this limitation, we introduce the concept of quasi-irreducibility in this paper. The adjacency tensor of a bipartite 2-graph is quasi-irreducible if that bipartite 2-graph is not bi-separable. This new concept reveals important spectral properties: although all M<sup>+</sup>-eigenvalues are M<sup>++</sup>-eigenvalues for irreducible nonnegative biquadratic tensors, the M<sup>+</sup>-eigenvalues of a quasi-irreducible nonnegative biquadratic tensor can be either M<sup>0</sup>-eigenvalues or M<sup>++</sup>-eigenvalues. Furthermore, we establish a max-min theorem for the M-spectral radius of a nonnegative biquadratic tensor.
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spelling doaj-art-e9aee2f047f547629ef2836da49badf42025-08-20T02:35:46ZengMDPI AGMathematics2227-73902025-06-011313206610.3390/math13132066Quasi-Irreducibility of Nonnegative Biquadratic TensorsLiqun Qi0Chunfeng Cui1Yi Xu2Jiangsu Provincial Scientific Research Center of Applied Mathematics, Nanjing 211189, ChinaSchool of Mathematical Sciences, Beihang University, Beijing 100191, ChinaJiangsu Provincial Scientific Research Center of Applied Mathematics, Nanjing 211189, ChinaWhile the adjacency tensor of a bipartite 2-graph is a nonnegative biquadratic tensor, it is inherently reducible. To address this limitation, we introduce the concept of quasi-irreducibility in this paper. The adjacency tensor of a bipartite 2-graph is quasi-irreducible if that bipartite 2-graph is not bi-separable. This new concept reveals important spectral properties: although all M<sup>+</sup>-eigenvalues are M<sup>++</sup>-eigenvalues for irreducible nonnegative biquadratic tensors, the M<sup>+</sup>-eigenvalues of a quasi-irreducible nonnegative biquadratic tensor can be either M<sup>0</sup>-eigenvalues or M<sup>++</sup>-eigenvalues. Furthermore, we establish a max-min theorem for the M-spectral radius of a nonnegative biquadratic tensor.https://www.mdpi.com/2227-7390/13/13/2066nonnegative biquadratic tensorsbipartite 2-graphsquasi-irreducibilityM<sup>0</sup>-eigenvaluesM<sup>++</sup>-eigenvaluesmax-min theorem
spellingShingle Liqun Qi
Chunfeng Cui
Yi Xu
Quasi-Irreducibility of Nonnegative Biquadratic Tensors
Mathematics
nonnegative biquadratic tensors
bipartite 2-graphs
quasi-irreducibility
M<sup>0</sup>-eigenvalues
M<sup>++</sup>-eigenvalues
max-min theorem
title Quasi-Irreducibility of Nonnegative Biquadratic Tensors
title_full Quasi-Irreducibility of Nonnegative Biquadratic Tensors
title_fullStr Quasi-Irreducibility of Nonnegative Biquadratic Tensors
title_full_unstemmed Quasi-Irreducibility of Nonnegative Biquadratic Tensors
title_short Quasi-Irreducibility of Nonnegative Biquadratic Tensors
title_sort quasi irreducibility of nonnegative biquadratic tensors
topic nonnegative biquadratic tensors
bipartite 2-graphs
quasi-irreducibility
M<sup>0</sup>-eigenvalues
M<sup>++</sup>-eigenvalues
max-min theorem
url https://www.mdpi.com/2227-7390/13/13/2066
work_keys_str_mv AT liqunqi quasiirreducibilityofnonnegativebiquadratictensors
AT chunfengcui quasiirreducibilityofnonnegativebiquadratictensors
AT yixu quasiirreducibilityofnonnegativebiquadratictensors