摘要
设图G是嵌入到欧拉示性数χ(∑)≥0的曲面∑上的图,χ′(G)和Δ(G)分别表示图G的边色数和最大度.如果△(G)≥4且G满足以下条件:(1)图G中的任意两个三角形T_1,T_2的距离至少是2;(2)图G中i-圈和j-圈的距离至少是1,i,j∈{3,4};(3)图G中没有5-圈,则有Δ(G)=χ′(G).
Let G be a graph embedded on a surface ∑ of Euler characteristic x(∑) ≥ 0.x’(G) and △(G) denote the chromatic index and the maximum degree of G,respectively.The paper shows that △(G) = x’(G) if the graph G with △(G) ≥ 4 satisfies the following properties:(1) any two triangles with distance at least two;(2) any i-cycle and j-cycle with distance at least one,i,j ∈ {3,4};(3) G contains no 5-cycles.
出处
《运筹学学报》
CSCD
北大核心
2015年第1期125-130,共6页
Operations Research Transactions
基金
新疆自治区高校科研计划项目(Nos.XJEDU2014S067
XJEDU2014I046)
关键词
欧拉示性数
圈
边色数
放电法
Euler characteristic
cycles
the chromatic index
discharging method