Hypergraphs with infinitely many extremal constructions
Discrete analysis (2023)
Cet article a éte moissonné depuis la source Scholastica
We give the first exact and stability results for a hypergraph Turán problem with infinitely many extremal constructions that are far from each other in edit-distance. This includes an example of triple systems with Turán density $2/9$, thus answering some questions posed by the third and fourth authors and Reiher about the feasible region of hypergraphs. Our results also provide extremal constructions whose shadow density is a transcendental number.
Our novel approach is to construct certain multilinear polynomials that attain their maximum (in the standard simplex) on a line segment and then to use these polynomials to define an operation on hypergraphs that gives extremal constructions.
@article{DAS_2023_a4,
author = {Jianfeng Hou and Heng Li and Xizhi Liu and Dhruv Mubayi and Yixiao Zhang},
title = {Hypergraphs with infinitely many extremal constructions},
journal = {Discrete analysis},
year = {2023},
language = {en},
url = {http://geodesic.mathdoc.fr/item/DAS_2023_a4/}
}
Jianfeng Hou; Heng Li; Xizhi Liu; Dhruv Mubayi; Yixiao Zhang. Hypergraphs with infinitely many extremal constructions. Discrete analysis (2023). http://geodesic.mathdoc.fr/item/DAS_2023_a4/