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arXiv 1402.0984math.CO
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伪随机图中Hamilton圈的幂

Powers of Hamilton cycles in pseudorandom graphs

Peter Allen, Julia Böttcher, Hiep Hàn, Yury Person, Yoshiharu Kohayakawa

摘要:

我们研究了伪随机图中Hamilton圈的幂的出现,使用以下相对弱的伪随机性概念。一个图$G$是$(\varepsilon,p,k,\ell)$ -伪随机的,如果对于所有不相交的$X$和$Y\subset V(G)$,有$|X|\ge\varepsilon p^kn$和$|Y|\ge\varepsilon p^\ell n$,我们有$e(X,Y)=(1\pm\varepsilon)p|X||Y|$。证明了对所有的$β>0$,存在一个$\varepsilon>0$使得在$n$顶点上的最小度至少为$βpn$的$(\varepsilon,p,1,2)$ -伪随机图包含一个Hamilton圈的平方.特别地,这意味着具有$λ\ll d^{5/2 }n^{-3/2}$的$(n,d,λ)$ -图包含哈密尔顿圈的平方,因此如果$n$是$3$的倍数,则包含三角形因子。这改进了Krivelevich,Sudakov和Szabó [Triangle factors in sparse pseudo-random graphs,Combinatorica 24(2004),no.3,403- 426]的结果。我们还将所得结果推广到Hamilton圈的高次幂上,并建立了相应的计数形式.

英文摘要:

We study the appearance of powers of Hamilton cycles in pseudorandom graphs, using the following comparatively weak pseudorandomness notion. A graph $G$ is $(\varepsilon,p,k,\ell)$-pseudorandom if for all disjoint $X$ and $Y\subset V(G)$ with $|X|\ge\varepsilon p^kn$ and $|Y|\ge\varepsilon p^\ell n$ we have $e(X,Y)=(1\pm\varepsilon)p|X||Y|$. We prove that for all $β>0$ there is an $\varepsilon>0$ such that an $(\varepsilon,p,1,2)$-pseudorandom graph on $n$ vertices with minimum degree at least $βpn$ contains the square of a Hamilton cycle. In particular, this implies that $(n,d,λ)$-graphs with $λ\ll d^{5/2 }n^{-3/2}$ contain the square of a Hamilton cycle, and thus a triangle factor if $n$ is a multiple of $3$. This improves on a result of Krivelevich, Sudakov and Szabó [Triangle factors in sparse pseudo-random graphs, Combinatorica 24 (2004), no. 3, 403--426]. We also extend our result to higher powers of Hamilton cycles and establish corresponding counting versions.

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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