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Clustered 3-colouring graphs of bounded degree

Published online by Cambridge University Press:  18 June 2021

Vida Dujmović
Affiliation:
School of Computer Science and Electrical Engineering, University of Ottawa, Ottawa, Canada
Louis Esperet
Affiliation:
Laboratoire G-SCOP (CNRS, Univ. Grenoble Alpes), Grenoble, France
Pat Morin
Affiliation:
School of Computer Science, Carleton University, Ottawa, Canada
Bartosz Walczak
Affiliation:
Department of Theoretical Computer Science, Faculty of Mathematics and Computer Science, Jagiellonian University, Kraków, Poland
David R. Wood*
Affiliation:
School of Mathematics, Monash University, Melbourne, Australia
*
*Corresponding author. Email: david.wood@monash.edu

Abstract

A (not necessarily proper) vertex colouring of a graph has clustering c if every monochromatic component has at most c vertices. We prove that planar graphs with maximum degree $\Delta$ are 3-colourable with clustering $O(\Delta^2)$. The previous best bound was $O(\Delta^{37})$. This result for planar graphs generalises to graphs that can be drawn on a surface of bounded Euler genus with a bounded number of crossings per edge. We then prove that graphs with maximum degree $\Delta$ that exclude a fixed minor are 3-colourable with clustering $O(\Delta^5)$. The best previous bound for this result was exponential in $\Delta$.

Information

Type
Paper
Copyright
© The Author(s), 2021. Published by Cambridge University Press

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