共 21 条
Sufficient conditions for component factors in a graph
被引:3
作者:
Chen, Hongzhang
[1
]
Lv, Xiaoyun
[1
]
Li, Jianxi
[2
]
机构:
[1] Lanzhou Univ, Gansu Ctr Appl Math, Sch Math & Stat, Lanzhou, Gansu, Peoples R China
[2] Minnan Normal Univ, Sch Math & Stat, Zhangzhou, Fujian, Peoples R China
基金:
中国国家自然科学基金;
关键词:
Component factor;
(Signless Laplacian) Spectral radius;
Laplacian eigenvalue;
Toughness;
Perfect k-matching;
EXISTENCE;
D O I:
10.1007/s13226-024-00575-7
中图分类号:
O1 [数学];
学科分类号:
0701 ;
070101 ;
摘要:
Let G be a graph and H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathcal {H}$$\end{document} be a set of connected graphs. A spanning subgraph H of G is called an H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathcal {H}$$\end{document}-factor if each component of H is isomorphic to a member of H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathcal {H}$$\end{document}. In this paper, we first present a lower bound on the size (resp. the spectral radius) of G to guarantee that G has a {P2,Cn:n >= 3}\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\{P_2,\, C_n: n\ge 3\}$$\end{document}-factor (or a perfect k-matching for even k) and construct extremal graphs to show all this bounds are best possible. We then provide a lower bound on the signless laplacian spectral radius of G to ensure that G has a {K1,j:1 <= j <= k}\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\{K_{1,j}:1\le j\le k\}$$\end{document}-factor, where k >= 2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$k\ge 2 $$\end{document} is an integer. Moreover, we also provide some Laplacian eigenvalue (resp. toughness) conditions for the existence of {P2,Cn:n >= 3}\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\{P_2,\, C_{n}:n\ge 3\}$$\end{document}-factor, P >= 3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P_{\ge 3}$$\end{document}-factor and {K1,j:1 <= j <= k}\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\{K_{1,j}: 1\le j\le k\}$$\end{document}-factor in G, respectively. Some of our results extend or improve the related existing results.
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页数:12
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