共查询到18条相似文献,搜索用时 93 毫秒
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通过引进(m,n)-洞的概念,推广了已有的结论,得到了(m,n)-树的一个新的充分必要条件. 相似文献
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(m,n)-树的一个充分必要条件 总被引:3,自引:0,他引:3
<正> 一、(m,n)-树的定义及有关结果 图论中树的概念在Beineke与Pippert的研究中已推广到高维空间.后来Dewdney又进一步把它推广到n维复形上去,得出了(m,n)-树的概念. 相似文献
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本文研究了n维复形上(m,n)-树的判定性质,并对(m,n)-树的-个充分必要条件进行了推广. 相似文献
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(m,n)—树的计数公式 总被引:1,自引:1,他引:0
Beineke和 Pippert[1,2 ] 将树的概念推广到高维空间 ,后来 Dewdney[3] 又进一步把它推广到 n维复形上 ,得到了 (m,n) —树的概念 .本文在 n维复形领域 ,利用 (m,n) —树的图论特征和组合的方法 ,独立地得出了顶点标号的 (m,n)—树的计数公式 . 相似文献
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Let (V, U) be the vertex-partition of tree T as a bipartite graph. T is called an (m,n)-tree if |V|=m and |U| = n. For given positive integers m,n and d, the maximum spectral radius of all (m,n)-trees on diameter d are obtained, and all extreme graphs are determined. 相似文献
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TAN Shang-wang GUO Ji-ming QI JianDepartment of Applied Mathematics Petroleum University Dongying China 《数学季刊》2004,19(1):57-62
Let T denote a tree with the diameter d(d≥2) and order n. Let P^*d,r,n-d-1denote the tree obtained by identifying the rth vertex of path Pd l and the center of starKl,K1,n-d-1, where r = r(d) is the integer part about d 2/2. Then p(T)≤ p(P^*d,r,n-d-1), andequality holds if and only if T≌P^*d,r,n-d-1 相似文献
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阶数为n,控制数为γ的树的集合记为Tn,γ(其中n≥max{12,2γ+1},γ≥3)。本文给出了Tn,γ中前三大的邻接谱半径以及它们对应的图。 相似文献
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The spectrum of weighted graphs are often used to solve the problems in the design of networks and electronic circuits. In this paper, we derive the sharp upper bound of spectral radius of all weighted trees on given order and edge independence number, and obtain all such trees that their spectral radius reach the upper bound. 相似文献
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给定染色数的无符号Laplace谱半径 总被引:2,自引:0,他引:2
设Gkn(k≥2)为n阶的染色数为k的连通图的集合.本文确定了Gkn中具有极大无符号Laplace谱半径的图,即k=2时为完全二部图,k≥3时为Turn图.本文也讨论了Gkn中的具有极小无符号Laplace谱半径的图,对k≤3的情形给出了此类图的刻画. 相似文献
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In this paper, we characterize the trees with the largest Laplacian and adjacency spectral radii among all trees with fixed number of vertices and fixed maximal degree, respectively. 相似文献
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A tricyclic graph G =(V(G), E(G)) is a connected and simple graph such that|E(G)| = |V(G)|+2. Let Tg nbe the set of all tricyclic graphs on n vertices with girth g. In this paper, we will show that there exists the unique graph which has the largest signless Laplacian spectral radius among all tricyclic graphs with girth g containing exactly three(resp., four)cycles. And at the same time, we also give an upper bound of the signless Laplacian spectral radius and the extremal graph having the largest signless Laplacian spectral radius in Tg n,where g is even. 相似文献