Vanishing codegree Tur\'{a}n density implies vanishing uniform Tur\'{a}n density
Abstract
For a -uniform hypergraph (or simply -graph) , the codegree Tur\'{a}n density is the infimum over all such that any -vertex -graph with every -subset of contained in at least edges has a copy of . The uniform Tur\'{a}n density is the supremum over all such that there are infinitely many -free -graphs satisfying that any linear-size subhypergraph of has edge density at least . Falgas-Ravry, Pikhurko, Vaughan and Volec [J. London Math. Soc., 2023] asked whether for every -graph , . We provide a positive answer to this question provided that . Our proof relies on a random geometric construction and a new formulation of the characterization of -graphs with vanishing uniform Tur\'{a}n density due to Reiher, R{\"o}dl and Schacht [J. London Math. Soc., 2018]. Along the way, we answer a question of Falgas-Ravry, Pikhurko, Vaughan and Volec about subhypergraphs with linear minimum codegree in uniformly dense hypergraphs in the negative.
Keywords
Cite
@article{arxiv.2312.02879,
title = {Vanishing codegree Tur\'{a}n density implies vanishing uniform Tur\'{a}n density},
author = {Laihao Ding and Hong Liu and Shuaichao Wang and Haotian Yang},
journal= {arXiv preprint arXiv:2312.02879},
year = {2023}
}
Comments
10 pages