New upper bounds for the chromatic number of a graph

被引:0
|
作者
Stacho, L [1 ]
机构
[1] Slovak Acad Sci, Inst Math, Dept Informat, Bratislava 84000 4, Slovakia
关键词
simple graph; chromatic number; degree of a vertex;
D O I
10.1002/1097-0118(200102)36:2<117::AID-JGT6>3.0.CO;2-7
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
We show that for any graph G, the chromatic number chi (G) less than or equal to Delta (2)(G) + 1, where Delta (2)(G) is the largest degree that a vertex nu can have subject to the condition that nu is adjacent to a vertex whose degree is at least as big as its own, Moreover, we show that the upper bound is best possible in the the following sense: If Delta (2)(G) greater than or equal to 3, then to determine whether chi (G) less than or equal to Delta (2)(G) is an NP-complete problem. (C) 2001 John Wiley & Sons, Inc.
引用
收藏
页码:117 / 120
页数:4
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