Injective colorings of sparse graphs

被引:43
作者
Cranston, Daniel W. [3 ,4 ]
Kim, Seog-Jin [2 ]
Yu, Gexin [1 ]
机构
[1] Coll William & Mary, Williamsburg, VA 23185 USA
[2] Konkuk Univ, Seoul, South Korea
[3] Rutgers State Univ, DIMACS, Piscataway, NJ USA
[4] Virginia Commonwealth Univ, Richmond, VA USA
基金
美国国家科学基金会;
关键词
Injective coloring; Maximum average degree; Planar graph; PLANAR GRAPHS; CHROMATIC NUMBER;
D O I
10.1016/j.disc.2010.07.003
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
Let mad(G) denote the maximum average degree (over all subgraphs) of G and let chi(i)(G) denote the injective chromatic number of G. We prove that if mad(G) < 5/2, then chi(i)(C) <= Delta(G) + 1; and if mad(G) < 42/19, then chi(i)(C) = Delta(C). Suppose that G is a planar graph with girth g(G) and Delta(G) >= 4. We prove that if chi(i)(G) >= 9, then chi(i)(G) <= Delta(G) + 1; similarly, if g(G) >= 13, then chi(i)(C) = Delta(C). (C) 2010 Elsevier B.V. All rights reserved.
引用
收藏
页码:2965 / 2973
页数:9
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