运筹学学报 ›› 2019, Vol. 23 ›› Issue (1): 104-110.doi: 10.15960/j.cnki.issn.1007-6093.2019.01.012

• 运筹学 • 上一篇    下一篇

不含5-圈和相邻4-圈的平面图的线性2-荫度的一个上界

陈宏宇1,*, 谭香2   

  1. 1. 上海应用技术大学理学院, 上海 201418;
    2. 山东财经大学数学与数量经济学院, 济南 250014
  • 收稿日期:2017-03-27 出版日期:2019-03-15 发布日期:2019-03-15
  • 通讯作者: 陈宏宇 E-mail:hongyuchen86@163.com
  • 基金资助:

    国家自然科学基金青年基金(No.11401386)

An upper bound of the linear 2-arboricity of planar graphs with neither 5-cycles nor adjacent 4-cycles

CHEN Hongyu1,*, TAN Xiang2   

  1. 1. School of Science, Shanghai Institute of Technology, Shanghai 201418, China;
    2. School of Mathematics and Quantitative Economics, Shandong University of Finance and Economics, Jinan 250014, China
  • Received:2017-03-27 Online:2019-03-15 Published:2019-03-15

摘要:

G的一个边分解是指将G分解成子图G1G2,…,Gm使得EG)=EG1)∪ EG2)∪…∪ EGm),且对于ijEGi)∩EGj)=∅.一个线性k-森林是指每个分支都是长度最多为k的路的图.图G的线性k-荫度lakG)是使得G可以边分解为m个线性k-森林的最小整数m.显然,la1G)是G的边色数χ'(G);laG)表示每条分支路是无限长度时的情况,即通常所说的G的线性荫度laG).利用权转移的方法研究平面图的线性2-荫度la2G).设G是不含有5-圈和相邻4-圈的平面图,证明了若G连通且δG)≥ 2,则G包含一条边xy使得dx)+dy)≤ 8或包含一个2-交错圈.根据这一结果得到其线性2-荫度的上界为?△/2?+4.

关键词: 平面图, 线性2-荫度,

Abstract:

An edge-partition of a graph G is a decomposition of G into subgraphs G1, G2,…, Gm such that E(G)=E(G1)∪ E(G2)∪…∪ E(Gm) and E(Gi)∩ E(Gj)=∅ for ij. A linear k-forest is a graph in which each component is a path of length at most k. The linear k-arboricity lak(G) of a graph G is the least integer m such that G can be edge-partitioned into m linear k-forests. For extremities, la1(G) is the edge chromatic number χ'(G) of G; la(G) representing the case when component paths have unlimited lengths is the ordinary linear arboricity la(G) of G. In this paper, we use the discharging method to study the linear 2-arboricity la2(G) of planar graphs. Let G be a planar graph with neither 5-cycles nor adjacent 4-cycles. We prove that if G is connected and δ(G) ≥ 2, then G contains an edge xy with d(x)+d(y) ≤ 8 or a 2-alternating cycle. By this result, we obtain the upper bound of the linear 2-arboricity of G is ?△/2?+4.

Key words: planar graph, linear 2-arboricity, cycle

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