On Stable Cutsets in General and Minimum Degree Constrained Graphs

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Hauptverfasser: Vroon, Mats, Bodlaender, Hans L.
Format: Preprint
Veröffentlicht: 2025
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author Vroon, Mats
Bodlaender, Hans L.
author_facet Vroon, Mats
Bodlaender, Hans L.
contents A stable cutset is a set of vertices $S$ of a connected graph, that is pairwise non-adjacent and when deleting $S$, the graph becomes disconnected. Determining the existence of a stable cutset in a graph is known to be NP-complete. In this paper, we introduce a new exact algorithm for Stable Cutset. By branching on graph configurations and using the $O^*(1.3645)$ algorithm for the (3,2)-Constraint Satisfaction Problem presented by Beigel and Eppstein, we achieve an improved running time of $O^*(1.2972^n)$. In addition, we investigate the Stable Cutset problem for graphs with a bound on the minimum degree $δ$. First, we show that if the minimum degree of a graph $G$ is at least $\frac{2}{3}(n-1)$, then $G$ does not contain a stable cutset. Furthermore, we provide a polynomial-time algorithm for graphs where $δ\geq \tfrac{1}{2}n$, and a similar kernelisation algorithm for graphs where $δ= \tfrac{1}{2}n - k$. Finally, we prove that Stable Cutset remains NP-complete for graphs with minimum degree $c$, where $c > 1$. We design an exact algorithm for this problem that runs in $O^*(λ^n)$ time, where $λ$ is the positive root of $x^{δ+ 2} - x^{δ+ 1} + 6$. This algorithm can also be applied to the \textsc{3-Colouring} problem with the same minimum degree constraint, leading to an improved exact algorithm as well.
format Preprint
id arxiv_https___arxiv_org_abs_2510_09432
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On Stable Cutsets in General and Minimum Degree Constrained Graphs
Vroon, Mats
Bodlaender, Hans L.
Data Structures and Algorithms
Computational Complexity
Discrete Mathematics
A stable cutset is a set of vertices $S$ of a connected graph, that is pairwise non-adjacent and when deleting $S$, the graph becomes disconnected. Determining the existence of a stable cutset in a graph is known to be NP-complete. In this paper, we introduce a new exact algorithm for Stable Cutset. By branching on graph configurations and using the $O^*(1.3645)$ algorithm for the (3,2)-Constraint Satisfaction Problem presented by Beigel and Eppstein, we achieve an improved running time of $O^*(1.2972^n)$. In addition, we investigate the Stable Cutset problem for graphs with a bound on the minimum degree $δ$. First, we show that if the minimum degree of a graph $G$ is at least $\frac{2}{3}(n-1)$, then $G$ does not contain a stable cutset. Furthermore, we provide a polynomial-time algorithm for graphs where $δ\geq \tfrac{1}{2}n$, and a similar kernelisation algorithm for graphs where $δ= \tfrac{1}{2}n - k$. Finally, we prove that Stable Cutset remains NP-complete for graphs with minimum degree $c$, where $c > 1$. We design an exact algorithm for this problem that runs in $O^*(λ^n)$ time, where $λ$ is the positive root of $x^{δ+ 2} - x^{δ+ 1} + 6$. This algorithm can also be applied to the \textsc{3-Colouring} problem with the same minimum degree constraint, leading to an improved exact algorithm as well.
title On Stable Cutsets in General and Minimum Degree Constrained Graphs
topic Data Structures and Algorithms
Computational Complexity
Discrete Mathematics
url https://arxiv.org/abs/2510.09432