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Toughness and normalized Laplacian eigenvalues of graphs

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Given a connected graph G , the toughness tau G is defined as the minimum value of the ratio |S|/omega(G-S), where S ranges over all vertex cut sets of G , and omega(G-S) is the number of connected components in the subgraph G - S obtained by deleting all vertices of S from G . In this paper, we provide a lower bound for the toughness tau(G) in terms of the maximum degree, minimum degree and normalized Laplacian eigenvalues of G . This can be viewed as a slight generalization of Brouwer's toughness conjecture, which was confirmed by Gu (2021). Furthermore, we give a characterization of those graphs attaining the two lower bounds regarding toughness and Laplacian eigenvalues provided by Gu and Haemers (2022). (c) 2022 Elsevier Inc. All rights reserved.

ToughnessNormalized Laplacian eigenvalueAlgebraic connectivitySPECTRUMCONNECTIVITYBOUNDS

Huang, Xueyi、Das, Kinkar Chandra、Zhu, Shunlai

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East China Univ Sci & Technol

Sungkyunkwan Univ

2022

Applied mathematics and computation

Applied mathematics and computation

EISCI
ISSN:0096-3003
年,卷(期):2022.425
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