Many 3-colorings of triangle-free planar graphs

被引:17
|
作者
Thomassen, Carsten [1 ]
机构
[1] Tech Univ Denmark, Dept Math, DK-2800 Lyngby, Denmark
关键词
planar graphs; many; 3-colorings;
D O I
10.1016/j.jctb.2006.06.005
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
Grotzsch proved that every planar triangle-free graph is 3-colorable. We prove that it has at least 2(n1/2)/20000 distinct 3-colorings where n is the number of vertices. If the graph has girth at least 5, then it has at least 2(n/10000) distinct list-colorings provided every vertex has at least three available colors. (c) 2006 Elsevier Inc. All rights reserved.
引用
收藏
页码:334 / 349
页数:16
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