




















A $k$-graph (or $k$-uniform hypergraph) $H$ is uniformly dense if the edge distribution of $H$ is uniformly dense with respect to every large collection of $k$-vertex cliques induced by sets of $(k-2)$-tuples. Reiher, Rödl and Schacht [Int. Math. Res. Not., 2018] proposed the study of the uniform Turán density $π_{k-2}(F)$ for given $k$-graphs $F$ in uniformly dense $k$-graphs. Meanwhile, they [J. London Math. Soc., 2018] characterized $k$-graphs $F$ satisfying $π_{k-2}(F)=0$ and showed that $π_{k-2}(\cdot)$ ``jumps" from 0 to at least $k^{-k}$. In particular, they asked whether there exist $3$-graphs $F$ with $π_{1}(F)$ equal or arbitrarily close to $1/27$. Recently, Garbe, Král' and Lamaison [arXiv:2105.09883] constructed some $3$-graphs with $π_{1}(F)=1/27$. In this paper, for any $k$-graph $F$, we give a lower bound of $π_{k-2}(F)$ based on a probabilistic framework, and provide a general theorem that reduces proving an upper bound on $π_{k-2}(F)$ to embedding $F$ in reduced $k$-graphs of the same density using the regularity method for $k$-graphs. By using this result and Ramsey theorem for multicolored hypergraphs, we extend the results of Garbe, Král' and Lamaison to $k\ge 3$. In other words, we give a sufficient condition for $k$-graphs $F$ satisfying $π_{k-2}(F)=k^{-k}$. Additionally, we also construct an infinite family of $k$-graphs with $π_{k-2}(F)=k^{-k}$.
此内容由惯性聚合(RSS阅读器)自动聚合整理,仅供阅读参考。 原文来自 — 版权归原作者所有。