共查询到16条相似文献,搜索用时 78 毫秒
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图的星色数是通常色数概念的推广.本文求出了几类由轮图导出的平面图的星色数.前两类是由3-或5-轮图经细分等构造出的,其星色数分别为2+2/(2n+1),2+3/(3n+1)和2+3/(3n-1).第三类平面图是由n-轮图经过Hajos构造得到的,其星色数为3+1/n.本类图的星色数结果推广了已有结论. 相似文献
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1988年,Vince定义了图的色数的一个推广——图的星色数,本文研究了有围长限制或有最大度限制的临界图的星色数,得到了三个新结果。 相似文献
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本文构造出了星色数为3+1/d,3+2(2d-1),3+3/(3d-1),和3+3/(3d-2)的一些平面图类,从而部分解决了Vince的问题. 相似文献
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肖仁兵邓伟升 《数学的实践与认识》2022,(9):180-187
一个图Γ称之为边本原图.若Γ的全自同构群作用在Γ的边集上是本原的.边本原图是一类重要的对称图,这类图不是很多,但一些著名的图,比如Heawood图,Tutte-Coxeter图和Higman-Sims图都是边本原图.我们通过构造陪集图的方法来研究边本原图,并给出了基柱为Mathieu群的几乎单群上边本原图的分类. 相似文献
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《数学的实践与认识》2017,(18)
图的EDS(偏心距离和)是图的一个类似于Wiener指数的另一个重要指数,近年来受到广泛的关注.2012年H.B.Hua等在Discrete Appl.Math.中的一篇关于图的EDS极图的论文中提出一个问题:哪些图是具有k个割点及最大或最小EDS的极图?通过研究图的EDS确定了给定割点数为k的简单连通图的最小EDS极图. 相似文献
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The concept of the star chromatic number of a graph was introduced by Vince (A. Vince, Star chromatic number, J. Graph Theory 12 (1988), 551–559), which is a natural generalization of the chromatic number of a graph. This paper calculates the star chromatic numbers of three infinite families of planar graphs. More precisely, the first family of planar graphs has star chromatic numbers consisting of two alternating infinite decreasing sequences between 3 and 4; the second family of planar graphs has star chromatic numbers forming an infinite decreasing sequence between 3 and 4; and the third family of planar graphs has star chromatic number 7/2. © 1998 John Wiley & Sons, Inc. J Graph Theory 27: 33–42, 1998 相似文献
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Bing Zhou 《Journal of Combinatorial Theory, Series B》1997,70(2):245-258
We investigate the notion of the star chromatic number of a graph in conjunction with various other graph parameters, among them, clique number, girth, and independence number. 相似文献
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三类笛卡尔积图的关联色数 总被引:2,自引:0,他引:2
图的关联色数的概念是 Brualdi和 Massey于 1 993年引入的 ,它同图的强色指数有密切的关系 .Guiduli[2 ] 说明关联色数是有向星萌度的一个特殊情况 ,迄今仅确定了某些特殊图类的关联色数 .本文给出了完全图与完全图、圈与完全图、圈与圈的笛卡尔积图的关联色数。 相似文献
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Andrew Lyons 《Discrete Applied Mathematics》2011,159(16):1842-1850
An acyclic coloring of a graph is a proper vertex coloring such that the union of any two color classes induces a disjoint collection of trees. The more restricted notion of star coloring requires that the union of any two color classes induces a disjoint collection of stars. We prove that every acyclic coloring of a cograph is also a star coloring and give a linear-time algorithm for finding an optimal acyclic and star coloring of a cograph. If the graph is given in the form of a cotree, the algorithm runs in O(n) time. We also show that the acyclic chromatic number, the star chromatic number, the treewidth plus 1, and the pathwidth plus 1 are all equal for cographs. 相似文献