K4-Free Graphs with No Odd Hole: Even Pairs and the Circular Chromatic Number

被引：2
|
作者：
Zwols, Yori [1 ]
机构：
[1] Columbia Univ, Dept Ind Engn & Operat Res, New York, NY 10027 USA
来源：
JOURNAL OF GRAPH THEORY | 2010年 / 65卷 / 04期
关键词：
forbidden induced subgraphs; circular chromatic number; even pairs; odd holes;
D O I：
10.1002/jgt.20482
中图分类号：
O1 [数学];
学科分类号：
0701 ; 070101 ;
摘要：
An odd hole in a graph is an induced cycle of odd length at least five. In this article we show that every imperfect K-4-free graph with no odd hole either is one of two basic graphs, or has an even pair or a clique cutset. We use this result to show that every K-4-free graph with no odd hole has circular chromatic number strictly smaller than 4. We also exhibit a sequence {H-n} of such graphs with lim(n ->infinity) chi(c)(H-n)=4. (C) 2010 Wiley Periodicals, Inc. J Graph Theory 65: 303-322, 2010
引用
收藏
页码：303 / 322
页数：20
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