Minimum degree stability of H-free graphs

<p>Given an $(r + 1)$-chromatic graph $H$, the fundamental edge stability result of Erdős and Simonovits says that all $n$-vertex $H$-free graphs have at most $(1 - 1/r + o(1)) \binom{n}{2}$ edges, and any $H$-free graph with that many edges can be made $r$-partite by deleting $o(n^{2})$ edges...

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主要作者: Illingworth, F
格式: Journal article
語言:English
出版: 2021
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author Illingworth, F
author_facet Illingworth, F
author_sort Illingworth, F
collection OXFORD
description <p>Given an $(r + 1)$-chromatic graph $H$, the fundamental edge stability result of Erdős and Simonovits says that all $n$-vertex $H$-free graphs have at most $(1 - 1/r + o(1)) \binom{n}{2}$ edges, and any $H$-free graph with that many edges can be made $r$-partite by deleting $o(n^{2})$ edges. Here we consider a natural variant of this -- the minimum degree stability of $H$-free graphs. In particular, what is the least $c$ such that any $n$-vertex $H$-free graph with minimum degree greater than $cn$ can be made $r$-partite by deleting $o(n^{2})$ edges? We determine this least value for all 3-chromatic $H$ and for very many non-3-colourable $H$ (all those in which one is commonly interested) as well as bounding it for the remainder. This extends the Andrásfai-Erdős-Sós theorem and work of Alon and Sudakov.</p>
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spelling oxford-uuid:1a369879-3bc3-4833-bdce-6be72f7154d22022-03-26T10:53:31ZMinimum degree stability of H-free graphsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:1a369879-3bc3-4833-bdce-6be72f7154d2EnglishSymplectic Elements2021Illingworth, F<p>Given an $(r + 1)$-chromatic graph $H$, the fundamental edge stability result of Erdős and Simonovits says that all $n$-vertex $H$-free graphs have at most $(1 - 1/r + o(1)) \binom{n}{2}$ edges, and any $H$-free graph with that many edges can be made $r$-partite by deleting $o(n^{2})$ edges. Here we consider a natural variant of this -- the minimum degree stability of $H$-free graphs. In particular, what is the least $c$ such that any $n$-vertex $H$-free graph with minimum degree greater than $cn$ can be made $r$-partite by deleting $o(n^{2})$ edges? We determine this least value for all 3-chromatic $H$ and for very many non-3-colourable $H$ (all those in which one is commonly interested) as well as bounding it for the remainder. This extends the Andrásfai-Erdős-Sós theorem and work of Alon and Sudakov.</p>
spellingShingle Illingworth, F
Minimum degree stability of H-free graphs
title Minimum degree stability of H-free graphs
title_full Minimum degree stability of H-free graphs
title_fullStr Minimum degree stability of H-free graphs
title_full_unstemmed Minimum degree stability of H-free graphs
title_short Minimum degree stability of H-free graphs
title_sort minimum degree stability of h free graphs
work_keys_str_mv AT illingworthf minimumdegreestabilityofhfreegraphs