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总览 评价 刘清海 1, , Xingxing Yu 2,* , 张昭 3, ( 1、 福州大学离散数学研究中心,福州 350108 ; 2、 School of Mathematics, Georgia Institute of Technology, Atlanta, Georgia, 30318, USA.; 3、 浙江师范大学数理信息学院,金华,浙江,321004;
刘清海1,, Xingxing Yu2,*, 张昭3,
(
1、福州大学离散数学研究中心,福州 350108 ; 2、School of Mathematics, Georgia Institute of Technology, Atlanta, Georgia, 30318, USA.; 3、浙江师范大学数理信息学院,金华,浙江,321004; )
摘要:
图的周长是指图的最长圈的长度,Bondy 猜想存在一个常数~$c$ 使得任意一个阶数为~$n$ 的三连通三正则图的周长至少为~$n^c$. 该猜想被~Jackson 证明,其中~$c=0.694$. Bilinsi 等人通过研究三边连通图中的欧拉子图又把界提高到了~$Omega(n^{0.753})$。 这篇文章中,我们通过考虑通过任意两条边(包括相邻和不相邻两种情况)的圈的方式进一步把下界提高到~$Omega(n^0.8)$.
关键词:
周长;三正则图;最长圈
Qinghai Liu1,, Xingxing Yu2,*, Zhao Zhang3,
(
1、Center for Discrete Mathematics, Fuzhou University, Fuzhou 350108 ; 2、School of Mathematics, Georgia Institute of Technology, Atlanta, Georgia, 30318, USA; 3、College of Mathematics Physics and Information Engineering, Zhejiang Normal University, Jinhua, Zhejiang, 321004, China; )
Abstract:
The circumference of a graph is the length of its longest cycles. Jackson established a conjecture of Bondy by showing that the circumference of a 3-connected cubic graph of order $n$ is $Omega(n^{0.694})$.Bilinski {it et al.} improved this lower bound to $Omega(n^{0.753})$ bystudying large Eulerian subgraphs in 3-edge-connected graphs.In this paper, we further improve this lower bound to $Omega(n^{0.8})$.This is done by considering certain 2-connected cubic graphs, finding cycles through two given edges, anddistinguishing the cases whether or not these edges are adjacent.
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