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arXiv 2402.05060math.CO
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关于多色Turán数

On multicolor Turán numbers

József Balogh, Anita Liebenau, Letícia Mattos, Natasha Morrison

AI总结:

本文推广了一类Turán型问题,定义多色子图与对应极值函数,给出$\text{ex}_{C_5}(C_3,n)$的上界并证明极图接近5-环的blow-up,且该上界在线性误差项内紧。

摘要:

我们研究Imolay、Karl、Nagy和Váli近期提出的一类Turán型问题的推广问题。设F为固定图,G是k个边不交的F拷贝的并,即$G = \bigcup_{i=1}^{k} F_i$,其中每个$F_i$都与固定图F同构,且对所有$i \neq j$,有$E(F_i)\bigcap E(F_j)=\text{ø}$。若子图$H\bigsubseteq G$满足对所有i,H与$F_i$至多共享一条边,则称H是多色的。定义$\text{ex}_F(H,n)$为最大的k值,使得存在n个顶点上的$G = \bigcup_{i=1}^{k} F_i$不含H的多色拷贝。我们证明了$\text{ex}_{C_5}(C_3,n) \text{≤} n^2/25 + 3n/25+o(n)$,且所有极图都接近5-环的blow-up结构。该界在线性误差项范围内是紧的。

英文摘要:

We address a problem which is a generalization of Turán-type problems recently introduced by Imolay, Karl, Nagy and Váli. Let $F$ be a fixed graph and let $G$ be the union of $k$ edge-disjoint copies of $F$, namely $G = \mathbin{\dot{\cup}}_{i=1}^{k} F_i$, where each $F_i$ is isomorphic to a fixed graph $F$ and $E(F_i)\cap E(F_j)=\emptyset$ for all $i \neq j$. We call a subgraph $H\subseteq G$ multicolored if $H$ and $F_i$ share at most one edge for all $i$. Define $\text{ex}_F(H,n)$ to be the maximum value $k$ such that there exists $G = \mathbin{\dot{\cup}}_{i=1}^{k} F_i$ on $n$ vertices without a multicolored copy of $H$. We show that $\text{ex}_{C_5}(C_3,n) \le n^2/25 + 3n/25+o(n)$ and that all extremal graphs are close to a blow-up of the 5-cycle. This bound is tight up to the linear error term.

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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