Strengthening Rödl's theorem

What can be said about the structure of graphs that do not contain an induced copy of some graph H? Rödl showed in the 1980s that every H-free graph has large parts that are very sparse or very dense. More precisely, let us say that a graph F on n vertices is ε-restricted if either F or its compleme...

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Main Authors: Chudnovsky, M, Scott, A, Seymour, P, Spirkl, S
Format: Journal article
Language:English
Published: Elsevier 2023
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author Chudnovsky, M
Scott, A
Seymour, P
Spirkl, S
author_facet Chudnovsky, M
Scott, A
Seymour, P
Spirkl, S
author_sort Chudnovsky, M
collection OXFORD
description What can be said about the structure of graphs that do not contain an induced copy of some graph H? Rödl showed in the 1980s that every H-free graph has large parts that are very sparse or very dense. More precisely, let us say that a graph F on n vertices is ε-restricted if either F or its complement has maximum degree at most εn. Rödl proved that for every graph H, and every ε > 0, every H-free graph G has a linear-sized set of vertices inducing an ε-restricted graph. We strengthen Rödl’s result as follows: for every graph H, and all ε > 0, every H-free graph can be partitioned into a bounded number of subsets inducing ε-restricted graphs.
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spelling oxford-uuid:37a0336a-57d8-42ab-94de-57fa114a2c1f2023-09-26T08:45:28ZStrengthening Rödl's theoremJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:37a0336a-57d8-42ab-94de-57fa114a2c1fEnglishSymplectic ElementsElsevier2023Chudnovsky, MScott, ASeymour, PSpirkl, SWhat can be said about the structure of graphs that do not contain an induced copy of some graph H? Rödl showed in the 1980s that every H-free graph has large parts that are very sparse or very dense. More precisely, let us say that a graph F on n vertices is ε-restricted if either F or its complement has maximum degree at most εn. Rödl proved that for every graph H, and every ε > 0, every H-free graph G has a linear-sized set of vertices inducing an ε-restricted graph. We strengthen Rödl’s result as follows: for every graph H, and all ε > 0, every H-free graph can be partitioned into a bounded number of subsets inducing ε-restricted graphs.
spellingShingle Chudnovsky, M
Scott, A
Seymour, P
Spirkl, S
Strengthening Rödl's theorem
title Strengthening Rödl's theorem
title_full Strengthening Rödl's theorem
title_fullStr Strengthening Rödl's theorem
title_full_unstemmed Strengthening Rödl's theorem
title_short Strengthening Rödl's theorem
title_sort strengthening rodl s theorem
work_keys_str_mv AT chudnovskym strengtheningrodlstheorem
AT scotta strengtheningrodlstheorem
AT seymourp strengtheningrodlstheorem
AT spirkls strengtheningrodlstheorem