首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4篇
  完全免费   1篇
  数学   5篇
  2018年   1篇
  2015年   1篇
  2011年   1篇
  2009年   1篇
  2008年   1篇
排序方式: 共有5条查询结果,搜索用时 156 毫秒
1
1.
In this paper, we prove that the average degree of Δ-critical graphs with Δ=6 is at least . It improves the known bound for the average degree of 6-critical graphs G with |V(G)|>39.  相似文献
2.
In 1968, Vizing proposed the following conjecture: If G=(V,E) is a Δ-critical graph of order n and size m, then . This conjecture has been verified for the cases of Δ≤5. In this paper, we prove that when Δ=4. It improves the known bound for Δ=4 when n>6.  相似文献
3.
Let N be the set of all positive integers. A list assignment of a graph G is a function L:V(G)?2N that assigns each vertex v a list L(v) for all vV(G). We say that G is L-(2,1)-choosable if there exists a function ? such that ?(v)L(v) for all vV(G), |?(u)??(v)|2 if u and v are adjacent, and |?(u)??(v)|1 if u and v are at distance 2. The list-L(2,1)-labeling number λl(G) of G is the minimum k such that for every list assignment L={L(v):|L(v)|=k,vV(G)}, G is L-(2,1)-choosable. We prove that if G is a planar graph with girth g8 and its maximum degree Δ is large enough, then λl(G)Δ+3. There are graphs with large enough Δ and g8 having λl(G)=Δ+3.  相似文献
4.
In 1968, Vizing [Uaspekhi Mat Nauk 23 (1968) 117–134; Russian Math Surveys 23 (1968), 125–142] conjectured that for any edge chromatic critical graph with maximum degree , . This conjecture has been verified for . In this article, by applying the discharging method, we prove the conjecture for . © 2008 Wiley Periodicals, Inc. J Graph Theory 60: 149–171, 2009  相似文献
5.
The 2-step domination problem is to find a minimum vertex set D of a graph such that every vertex of the graph is either in D or at distance two from some vertex of D.In the present paper,by using a labeling method,we provide an O(m) time algorithm to solve the2-step domination problem on block graphs,a superclass of trees.  相似文献
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号