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arXiv 2303.11206math.CO
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随机图中的规范着色

Canonical colourings in random graphs

Nina Kamčev, Mathias Schacht

AI总结:

本研究将确定性场景下的Erdős-Rado规范着色定理推广到随机图环境,证明当ℓ≥4时,随机图规范着色性质的阈值与Rödl-Ruciński拉姆齐阈值一致,核心贡献为借助Conlon-Gowers迁移原理完成1-命题证明。

摘要:

Rödl与Ruciński(1990年)建立了随机图的拉姆齐定理。具体而言,对于固定整数$r$、$\ell\geq2$,他们证明了$\hat p_{K_\ell,r}(n)=n^{-\frac{2}{\ell+1}}$是拉姆齐性质的阈值:即二项随机图$G(n,p)$的边的每一种$r$着色都会产生一个单色的$K_\ell$副本。我们研究该结果如何推广到颜色数无界的$G(n,p)$任意着色情形。在确定性场景下,Erdős和Rado证明了可以保证存在规范着色的$K_\ell$副本。我们将Erdős-Rado定理迁移到随机环境中,并证明当$\text{ell}\geq4$时,两个阈值是一致的。作为推论,该证明得到了不含$K_{\ell+1}$的图$G$,其每一种边着色都包含一个规范着色的$K_\ell$。该阈值的0-命题是Rödl-Ruciński定理对应命题的直接推论,核心贡献在于1-命题的证明,该证明运用了Conlon和Gowers的迁移原理。

英文摘要:

Rödl and Ruciński (1990) established Ramsey's theorem for random graphs. In particular, for fixed integers $r$, $\ell\geq 2$ they showed that $\hat p_{K_\ell,r}(n)=n^{-\frac{2}{\ell+1}}$ is a threshold for the Ramsey property that every $r$-colouring of the edges of the binomial random graph $G(n,p)$ yields a monochromatic copy of $K_\ell$. We investigate how this result extends to arbitrary colourings of $G(n,p)$ with an unbounded number of colours. In this situation, Erdős and Rado showed that canonically coloured copies of $K_\ell$ can be ensured in the deterministic setting. We transfer the Erdős-Rado theorem to the random environment and show that both thresholds coincide for $\ell\geq 4$. As a consequence, the proof yields $K_{\ell+1}$-free graphs $G$ for which every edge colouring contains a canonically coloured $K_\ell$. The $0$-statement of the threshold is a direct consequence of the corresponding statement of the Rödl-Ruciński theorem and the main contribution is the $1$-statement. The proof of the $1$-statement employs the transference principle of Conlon and Gowers.

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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