Pushing the frontiers of subexponential FPT time for Feedback Vertex Set

Fuente: arXiv
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Main Authors: Berthe, Gaétan, Bougeret, Marin, Gonçalves, Daniel, Raymond, Jean-Florent
Format: Preprint
Published: 2025
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author Berthe, Gaétan
Bougeret, Marin
Gonçalves, Daniel
Raymond, Jean-Florent
author_facet Berthe, Gaétan
Bougeret, Marin
Gonçalves, Daniel
Raymond, Jean-Florent
contents The paper deals with the Feedback Vertex Set problem parameterized by the solution size. Given a graph $G$ and a parameter $k$, one has to decide if there is a set $S$ of at most $k$ vertices such that $G-S$ is acyclic. Assuming the Exponential Time Hypothesis, it is known that FVS cannot be solved in time $2^{o(k)}n^{\mathcal{O}(1)}$ in general graphs. To overcome this, many recent results considered FVS restricted to particular intersection graph classes and provided such $2^{o(k)}n^{\mathcal{O}(1)}$ algorithms. In this paper we provide generic conditions on a graph class for the existence of an algorithm solving FVS in subexponential FPT time, i.e. time $2^{k^\varepsilon} \mathop{\rm poly}(n)$, for some $\varepsilon<1$, where $n$ denotes the number of vertices of the instance and $k$ the parameter. On the one hand this result unifies algorithms that have been proposed over the years for several graph classes such as planar graphs, map graphs, unit-disk graphs, pseudo-disk graphs, and string graphs of bounded edge-degree. On the other hand it extends the tractability horizon of FVS to new classes that are not amenable to previously used techniques, in particular intersection graphs of ``thin'' objects like segment graphs or more generally $s$-string graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2504_17708
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Pushing the frontiers of subexponential FPT time for Feedback Vertex Set
Berthe, Gaétan
Bougeret, Marin
Gonçalves, Daniel
Raymond, Jean-Florent
Data Structures and Algorithms
The paper deals with the Feedback Vertex Set problem parameterized by the solution size. Given a graph $G$ and a parameter $k$, one has to decide if there is a set $S$ of at most $k$ vertices such that $G-S$ is acyclic. Assuming the Exponential Time Hypothesis, it is known that FVS cannot be solved in time $2^{o(k)}n^{\mathcal{O}(1)}$ in general graphs. To overcome this, many recent results considered FVS restricted to particular intersection graph classes and provided such $2^{o(k)}n^{\mathcal{O}(1)}$ algorithms. In this paper we provide generic conditions on a graph class for the existence of an algorithm solving FVS in subexponential FPT time, i.e. time $2^{k^\varepsilon} \mathop{\rm poly}(n)$, for some $\varepsilon<1$, where $n$ denotes the number of vertices of the instance and $k$ the parameter. On the one hand this result unifies algorithms that have been proposed over the years for several graph classes such as planar graphs, map graphs, unit-disk graphs, pseudo-disk graphs, and string graphs of bounded edge-degree. On the other hand it extends the tractability horizon of FVS to new classes that are not amenable to previously used techniques, in particular intersection graphs of ``thin'' objects like segment graphs or more generally $s$-string graphs.
title Pushing the frontiers of subexponential FPT time for Feedback Vertex Set
topic Data Structures and Algorithms
url https://arxiv.org/abs/2504.17708