Discrete and metric divisorial gonality can be different

Journal Article (2022)
Author(s)

Josse van Dobben de Bruyn (TU Delft - Electrical Engineering, Mathematics and Computer Science)

Harry Smit (Max Planck Institute for Mathematics)

Marieke van der Wegen (Universiteit Utrecht)

Research Group
Discrete Mathematics and Optimization
DOI related publication
https://doi.org/10.1016/j.jcta.2022.105619 Final published version
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Publication Year
2022
Language
English
Research Group
Discrete Mathematics and Optimization
Journal title
Journal of Combinatorial Theory. Series A
Volume number
189
Article number
105619
Pages (from-to)
1-19
Downloads counter
225
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Abstract

This paper compares the divisorial gonality of a finite graph G to the divisorial gonality of the associated metric graph Γ(G,1) with unit lengths. We show that dgon(Γ(G,1)) is equal to the minimal divisorial gonality of all regular subdivisions of G, and we provide a class of graphs for which this number is strictly smaller than the divisorial gonality of G. This settles a conjecture of M. Baker [3, Conjecture 3.14] in the negative.