arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1903.08232math.CO
收藏

3-一致超图中2-独立集的最大化

Maximizing 2-Independent Sets in 3-Uniform Hypergraphs

Lauren Keough, A. J. Radcliffe

摘要:

最近有兴趣在图中的独立集的数量最大化。例如,Kahn-Zhao定理给出了$d$ -正则图中独立集个数的上界。类似地,它是Kruskal-Katona定理的推论,lex图在固定大小和阶的图中具有最大数量的独立集。在本文中,我们解决了两个等价的问题。第一个是:什么样的$3$ -均匀超图在基集上的大小为$n$,至少有$t$边,具有最多的$2$ -独立集?这里,$2$ -独立集是顶点的子集,其包含来自每条边的少于$2$的顶点。这等价于确定在至少具有$t$三角形的$n$顶点上的哪个图具有最多独立集的问题。(超图)的答案是,忽略一些暂时的和一些持久的异常,一个$(2,3,1)$ -lex风格的$3$ -图是最佳的。我们还讨论了固定大小和阶的$r$ -一致超图中最大化$s$ -独立集的个数的问题,证明了一些简单的结果,并猜想了该问题的渐近正确的一般解.

英文摘要:

There has been interest recently in maximizing the number of independent sets in graphs. For example, the Kahn-Zhao theorem gives an upper bound on the number of independent sets in a $d$-regular graph. Similarly, it is a corollary of the Kruskal-Katona theorem that the lex graph has the maximum number of independent sets in a graph of fixed size and order. In this paper we solve two equivalent problems. The first is: what $3$-uniform hypergraph on a ground set of size $n$, having at least $t$ edges, has the most $2$-independent sets? Here a $2$--independent set is a subset of vertices containing fewer than $2$ vertices from each edge. This is equivalent to the problem of determining which graph on $n$ vertices having at least $t$ triangles has the most independent sets. The (hypergraph) answer is that, ignoring some transient and some persistent exceptions, a $(2,3,1)$-lex style $3$-graph is optimal. We also discuss the problem of maximizing the number of $s$-independent sets in $r$-uniform hypergraphs of fixed size and order, proving some simple results, and conjecture an asymptotically correct general solution to the problem.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑