The Complexity of Temporal Vertex Cover in Small-Degree Graphs

Fuente: arXiv
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Autores principales: Hamm, Thekla, Klobas, Nina, Mertzios, George B., Spirakis, Paul G.
Formato: Preprint
Publicado: 2022
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author Hamm, Thekla
Klobas, Nina
Mertzios, George B.
Spirakis, Paul G.
author_facet Hamm, Thekla
Klobas, Nina
Mertzios, George B.
Spirakis, Paul G.
contents Temporal graphs naturally model graphs whose underlying topology changes over time. Recently, the problems TEMPORAL VERTEX COVER (or TVC) and SLIDING-WINDOW TEMPORAL VERTEX COVER(or $Δ$-TVC for time-windows of a fixed-length $Δ$) have been established as natural extensions of the classic problem VERTEX COVER on static graphs with connections to areas such as surveillance in sensor networks. In this paper we initiate a systematic study of the complexity of TVC and $Δ$-TVC on sparse graphs. Our main result shows that for every $Δ\geq 2$, $Δ$-TVC is NP-hard even when the underlying topology is described by a path or a cycle. This resolves an open problem from literature and shows a surprising contrast between $Δ$-TVC and TVC for which we provide a polynomial-time algorithm in the same setting. To circumvent this hardness, we present a number of exact and approximation algorithms for temporal graphs whose underlying topologies are given by a path, that have bounded vertex degree in every time step, or that admit a small-sized temporal vertex cover.
format Preprint
id arxiv_https___arxiv_org_abs_2204_04832
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle The Complexity of Temporal Vertex Cover in Small-Degree Graphs
Hamm, Thekla
Klobas, Nina
Mertzios, George B.
Spirakis, Paul G.
Data Structures and Algorithms
Discrete Mathematics
Temporal graphs naturally model graphs whose underlying topology changes over time. Recently, the problems TEMPORAL VERTEX COVER (or TVC) and SLIDING-WINDOW TEMPORAL VERTEX COVER(or $Δ$-TVC for time-windows of a fixed-length $Δ$) have been established as natural extensions of the classic problem VERTEX COVER on static graphs with connections to areas such as surveillance in sensor networks. In this paper we initiate a systematic study of the complexity of TVC and $Δ$-TVC on sparse graphs. Our main result shows that for every $Δ\geq 2$, $Δ$-TVC is NP-hard even when the underlying topology is described by a path or a cycle. This resolves an open problem from literature and shows a surprising contrast between $Δ$-TVC and TVC for which we provide a polynomial-time algorithm in the same setting. To circumvent this hardness, we present a number of exact and approximation algorithms for temporal graphs whose underlying topologies are given by a path, that have bounded vertex degree in every time step, or that admit a small-sized temporal vertex cover.
title The Complexity of Temporal Vertex Cover in Small-Degree Graphs
topic Data Structures and Algorithms
Discrete Mathematics
url https://arxiv.org/abs/2204.04832