Phase transitions of the Erdős-Gyárfás function

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Hauptverfasser: Hu, Xinyu, Lin, Qizhong, Lu, Xin, Wang, Guanghui
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Veröffentlicht: 2025
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author Hu, Xinyu
Lin, Qizhong
Lu, Xin
Wang, Guanghui
author_facet Hu, Xinyu
Lin, Qizhong
Lu, Xin
Wang, Guanghui
contents Given positive integers $p,q$. For any integer $k\ge2$, an edge coloring of the complete $k$-graph $K_n^{(k)}$ is said to be a $(p,q)$-coloring if every copy of $K_p^{(k)}$ receives at least $q$ colors. The Erdős-Gyárfás function $f_k(n,p,q)$ is the minimum number of colors that are needed for $K_n^{(k)}$ to have a $(p,q)$-coloring. Conlon, Fox, Lee and Sudakov (\emph{IMRN, 2015}) conjectured that for any positive integers $p, k$ and $i$ with $k\ge3$ and $1\le i<k$, $f_k(n,p,{{p-i}\choose{k-i}})=(\log_{(i-1)}n)^{o(1)}$, where $\log_{(i)}n$ is an iterated $i$-fold logarithm in $n$. It has been verified to be true for $k=3, p=4, i=1$ by Conlon et. al (\emph{IMRN, 2015}), for $k=3, p=5, i=2$ by Mubayi (\emph{JGT, 2016}), and for all $k\ge 4, p=k+1,i=1$ by B. Janzer and O. Janzer (\emph{JCTB, 2024}). In this paper, we give new constructions and show that this conjecture holds for infinitely many new cases, i.e., it holds for all $k\ge4$, $p=k+2$ and $i=k-1$.
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id arxiv_https___arxiv_org_abs_2504_05647
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Phase transitions of the Erdős-Gyárfás function
Hu, Xinyu
Lin, Qizhong
Lu, Xin
Wang, Guanghui
Combinatorics
Given positive integers $p,q$. For any integer $k\ge2$, an edge coloring of the complete $k$-graph $K_n^{(k)}$ is said to be a $(p,q)$-coloring if every copy of $K_p^{(k)}$ receives at least $q$ colors. The Erdős-Gyárfás function $f_k(n,p,q)$ is the minimum number of colors that are needed for $K_n^{(k)}$ to have a $(p,q)$-coloring. Conlon, Fox, Lee and Sudakov (\emph{IMRN, 2015}) conjectured that for any positive integers $p, k$ and $i$ with $k\ge3$ and $1\le i<k$, $f_k(n,p,{{p-i}\choose{k-i}})=(\log_{(i-1)}n)^{o(1)}$, where $\log_{(i)}n$ is an iterated $i$-fold logarithm in $n$. It has been verified to be true for $k=3, p=4, i=1$ by Conlon et. al (\emph{IMRN, 2015}), for $k=3, p=5, i=2$ by Mubayi (\emph{JGT, 2016}), and for all $k\ge 4, p=k+1,i=1$ by B. Janzer and O. Janzer (\emph{JCTB, 2024}). In this paper, we give new constructions and show that this conjecture holds for infinitely many new cases, i.e., it holds for all $k\ge4$, $p=k+2$ and $i=k-1$.
title Phase transitions of the Erdős-Gyárfás function
topic Combinatorics
url https://arxiv.org/abs/2504.05647