Algebraic approach to stability results for Erdős-Ko-Rado theorem

Fuente: arXiv
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Main Authors: Ge, Gennian, Xu, Zixiang, Zhao, Xiaochen
Format: Preprint
Published: 2024
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_version_ 1866910678288171008
author Ge, Gennian
Xu, Zixiang
Zhao, Xiaochen
author_facet Ge, Gennian
Xu, Zixiang
Zhao, Xiaochen
contents Celebrated results often unfold like episodes in a long-running series. In the field of extremal set thoery, Erdős, Ko, and Rado in 1961 established that any $k$-uniform intersecting family on $[n]$ has a maximum size of $\binom{n-1}{k-1}$, with the unique extremal structure being a star. In 1967, Hilton and Milner followed up with a pivotal result, showing that if such a family is not a star, its size is at most $\binom{n-1}{k-1} - \binom{n-k-1}{k-1} + 1$, and they identified the corresponding extremal structures. In recent years, Han and Kohayakawa, Kostochka and Mubayi, and Huang and Peng have provided the second and third levels of stability results in this line of research. In this paper, we provide a unified approach to proving the stability result for the Erdős-Ko-Rado theorem at any level. Our framework primarily relies on a robust linear algebra method, which leverages appropriate non-shadows to effectively handle the structural complexities of these intersecting families.
format Preprint
id arxiv_https___arxiv_org_abs_2410_22676
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Algebraic approach to stability results for Erdős-Ko-Rado theorem
Ge, Gennian
Xu, Zixiang
Zhao, Xiaochen
Combinatorics
05D05
Celebrated results often unfold like episodes in a long-running series. In the field of extremal set thoery, Erdős, Ko, and Rado in 1961 established that any $k$-uniform intersecting family on $[n]$ has a maximum size of $\binom{n-1}{k-1}$, with the unique extremal structure being a star. In 1967, Hilton and Milner followed up with a pivotal result, showing that if such a family is not a star, its size is at most $\binom{n-1}{k-1} - \binom{n-k-1}{k-1} + 1$, and they identified the corresponding extremal structures. In recent years, Han and Kohayakawa, Kostochka and Mubayi, and Huang and Peng have provided the second and third levels of stability results in this line of research. In this paper, we provide a unified approach to proving the stability result for the Erdős-Ko-Rado theorem at any level. Our framework primarily relies on a robust linear algebra method, which leverages appropriate non-shadows to effectively handle the structural complexities of these intersecting families.
title Algebraic approach to stability results for Erdős-Ko-Rado theorem
topic Combinatorics
05D05
url https://arxiv.org/abs/2410.22676