当前位置: X-MOL 学术J. Comb. Theory A › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Chromatic numbers of Kneser-type graphs
Journal of Combinatorial Theory Series A ( IF 0.9 ) Pub Date : 2020-01-23 , DOI: 10.1016/j.jcta.2019.105188
Dmitriy Zakharov

Let G(n,r,s) be a graph whose vertices are all r-element subsets of an n-element set, in which two vertices are adjacent if they intersect in exactly s elements. In this paper we study chromatic numbers of G(n,r,s) with r,s being fixed constants and n tending to infinity. Using a recent result of Keevash on existence of designs we deduce an inequality χ(G(n,r,s))(1+o(1))nrs(rs1)!(2r2s1)! for r>s with r,s fixed constants. This inequality gives sharp upper bounds for r2s+1. Also we develop an elementary approach to this problem and prove that χ(G(n,4,2))n26 without use of Keevash's results.

Some bounds on the list chromatic number of G(n,r,s) are also obtained.



中文翻译:

Kneser型图的色数

Gñ[Rs是其顶点是所有的曲线图ř一个的子集-元素Ñ -元素集合,其中两个顶点是如果它们在正好相交相邻小号元件。在本文中,我们研究了Gñ[Rs[Rs是固定常数且n趋于无穷大。利用Keevash在设计存在方面的最新结果,我们得出了不等式χGñ[Rs1个+Ø1个ñ[R-s[R-s-1个2[R-2s-1个 对于 [R>s[Rs固定常数。这种不平等为[R2s+1个。此外,我们还针对该问题开发了一种基本方法,并证明了χGñ42ñ26 不使用Keevash的结果。

列表色数上的一些界限 Gñ[Rs 也获得。

更新日期:2020-01-23
down
wechat
bug