arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.03920math.CO
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稀疏随机二部图的平面性与亏格

Planarity and genus of sparse random bipartite graphs

Tuan Anh Do, Joshua Erde, Mihyun Kang

摘要:

二项式随机图$G(n,p)$的亏格对于大范围的$p=p(n)$是很好理解的。最近,Mohar和Ying开始研究随机二部图$G(n_1,n_2,p)$的亏格,其划分类的大小为$n_1$和$n_2$,他们表明当$n_1$和$n_2$的大小相当并且$p=p(n_1,n_2)$显著大于$(n_1n_2)^{-\frac{1}{2}}$时,随机二部图的亏格具有与二项式随机图相似的行为。本文证明了随机二部图在$p=(n_1n_2)^{-\frac{1}{2}}$上的平面性存在一个阈值,并研究了接近这个阈值的亏格,推广了Mohar和Ying的结果。事实证明,有定性不同的行为的情况下,$n_1$和$n_2$是可比的,当whp的属是线性的边数,比在$n_1$的情况下,渐近小于$n_2$,当whp的属的行为就像一个稀疏的随机图$G(n_1,q)$的属适当选择的$q=q(p,n_1,n_2)$。

英文摘要:

The genus of the binomial random graph $G(n,p)$ is well understood for a wide range of $p=p(n)$. Recently, the study of the genus of the random bipartite graph $G(n_1,n_2,p)$, with partition classes of size $n_1$ and $n_2$, was initiated by Mohar and Ying, who showed that when $n_1$ and $n_2$ are comparable in size and $p=p(n_1,n_2)$ is significantly larger than $(n_1n_2)^{-\frac{1}{2}}$ the genus of the random bipartite graph has a similar behaviour to that of the binomial random graph. In this paper we show that there is a threshold for planarity of the random bipartite graph at $p=(n_1n_2)^{-\frac{1}{2}}$ and investigate the genus close to this threshold, extending the results of Mohar and Ying. It turns out that there is qualitatively different behaviour in the case where $n_1$ and $n_2$ are comparable, when whp the genus is linear in the number of edges, than in the case where $n_1$ is asymptotically smaller than $n_2$, when whp the genus behaves like the genus of a sparse random graph $G(n_1,q)$ for an appropriately chosen $q=q(p,n_1,n_2)$.

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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