Coarse Balanced Separators and Tree-Decompositions

Fuente: arXiv
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Hauptverfasser: Chudnovsky, Maria, Hickingbotham, Robert
Format: Preprint
Veröffentlicht: 2025
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author Chudnovsky, Maria
Hickingbotham, Robert
author_facet Chudnovsky, Maria
Hickingbotham, Robert
contents A classical result of Robertson and Seymour (1986) states that the treewidth of a graph is linearly tied to its separation number: the smallest integer $k$ such that, for every weighting of the vertices, the graph admits a balanced separator of size at most $k$. Motivated by recent progress on coarse treewidth, Abrishami, Czyżewska, Kluk, Pilipczuk, Pilipczuk, and Rzążewski (2025) conjectured a coarse analogue to this result: every graph that has a balanced separator consisting of a bounded number of balls of bounded radius is quasi-isometric to a graph with bounded treewidth. In this paper, we confirm their conjecture for $K_{t,t}$-induced-subgraph-free graphs when the separator consists of a bounded number of balls of radius $1$. In doing so, we bridge two important conjectures concerning the structure of graphs that exclude a planar graph as an induced minor.
format Preprint
id arxiv_https___arxiv_org_abs_2505_06550
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Coarse Balanced Separators and Tree-Decompositions
Chudnovsky, Maria
Hickingbotham, Robert
Combinatorics
A classical result of Robertson and Seymour (1986) states that the treewidth of a graph is linearly tied to its separation number: the smallest integer $k$ such that, for every weighting of the vertices, the graph admits a balanced separator of size at most $k$. Motivated by recent progress on coarse treewidth, Abrishami, Czyżewska, Kluk, Pilipczuk, Pilipczuk, and Rzążewski (2025) conjectured a coarse analogue to this result: every graph that has a balanced separator consisting of a bounded number of balls of bounded radius is quasi-isometric to a graph with bounded treewidth. In this paper, we confirm their conjecture for $K_{t,t}$-induced-subgraph-free graphs when the separator consists of a bounded number of balls of radius $1$. In doing so, we bridge two important conjectures concerning the structure of graphs that exclude a planar graph as an induced minor.
title Coarse Balanced Separators and Tree-Decompositions
topic Combinatorics
url https://arxiv.org/abs/2505.06550