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arXiv · 2208.03573

Computing higher graph gonality is hard

Ralph Morrison·Lucas Tolley
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Abstract

In the theory of divisors on multigraphs, the $r^{th}$ divisorial gonality of a graph is the minimum degree of a rank $r$ divisor on that graph. It was proved by Gijswijt et al. that the first divisorial gonality of a finite graph is NP-hard to compute. We generalize their argument to prove that it is NP-hard to compute the $r^{th}$ divisorial gonality of a finite graph for all $r$. We use this result to prove that it is NP-hard to compute $r^{th}$ stable divisorial gonality for a finite graph, and to compute $r^{th}$ divisorial gonality for a metric graph. We also prove these problems are APX-hard, and we study the NP-completeness of these problems.

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Ralph Morrison, Lucas Tolley. 2022-08-06. Computing higher graph gonality is hard. https://arxiv.org/abs/2208.03573

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