arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1405.0107math.CO
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$σ$ -超图的独立性与匹配

Independence and Matchings in $σ$-hypergraphs

Yair Caro, Josef Lauri, Christina Zarb

摘要:

设$σ$是正整数$r$的一个划分。$σ$ -超图$H=H(n,r,q|σ)$是$nq$顶点上的$r$ -一致超图,这些顶点被划分为$n$类$V_1, V_2, \ldots, V_n$,每个类包含$q$顶点.如果由非零基数$|K\cap V_i|, 1\leq i \leq n,$形成的$r$的划分是$σ$,则顶点的$r$ -子集$K$是超图的边.在早期的作品中,我们已经考虑了着色的顶点$H$的约束,使任何边缘至少有$α$和最$β$顶点相同的颜色,我们已经表明,有趣的结果可以通过改变$α, β$和$H$的参数适当。在本文中,我们继续研究的通用性$σ$ -超图考虑两个经典的问题:独立性和匹配。我们首先证明了一个有趣的链接之间的约束着色和$k$ -独立数的超图,也就是说,最大的基数的顶点子集的超图不包含$k+1$顶点在同一条边。我们还给出了$σ$ -超图$H$的$k$ -独立数的精确计算.然后,我们提出的结果最大,有时完美,匹配$H$。这些结果往往取决于$H$的参数之间的可分性关系和$σ$的部分的最高公因子。

英文摘要:

Let $σ$ be a partition of the positive integer $r$. A $σ$-hypergraph $H=H(n,r,q|σ)$ is an $r$-uniform hypergraph on $nq$ vertices which are partitioned into $n$ classes $V_1, V_2, \ldots, V_n$ each containing $q$ vertices. An $r$-subset $K$ of vertices is an edge of the hypergraph if the partition of $r$ formed by the non-zero cardinalities $|K\cap V_i|, 1\leq i \leq n,$ is $σ$. In earlier works we have considered colourings of the vertices of $H$ which are constrained such that any edge has at least $α$ and at most $β$ vertices of the same colour, and we have shown that interesting results can be obtained by varying $α, β$ and the parameters of $H$ appropriately. In this paper we continue to investigate the versatility of $σ$-hypergraphs by considering two classical problems: independence and matchings. We first demonstrate an interesting link between the constrained colourings described above and the $k$-independence number of a hypergraph, that is, the largest cardinality of a subset of vertices of a hypergraph not containing $k+1$ vertices in the same edge. We also give an exact computation of the $k$-independence number of the $σ$-hypergraph $H$. We then present results on maximum, and sometimes perfect, matchings in $H$. These results often depend on divisibility relations between the parameters of $H$ and on the highest common factor of the parts of $σ$.

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。

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