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Bibliographic Details
Main Authors: Silva, Lucas de Oliveira, Pedrosa, Lehilton Lelis Chaves
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.14357
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author Silva, Lucas de Oliveira
Pedrosa, Lehilton Lelis Chaves
author_facet Silva, Lucas de Oliveira
Pedrosa, Lehilton Lelis Chaves
contents The Freeze-Tag Problem (FTP) is a scheduling problem with application in robot swarm activation and was introduced by Arkin et al. in 2002. This problem seeks an efficient way of activating a robot swarm, starting with a single active robot. Activations occur through direct contact, and once a robot becomes active, it can move and help activate other robots. Although the problem has been shown to be NP-hard in the Euclidean plane $\mathbb{R}^2$ under the $L_2$ distance, and in three-dimensional Euclidean space $\mathbb{R}^3$ under any $L_p$ distance with $p \ge 1$, its complexity under the $L_1$ (Manhattan) distance in $\mathbb{R}^2$ has remained an open question. In this paper, we settle this question by proving that FTP is strongly NP-hard in the Euclidean plane with $L_1$ distance.
format Preprint
id arxiv_https___arxiv_org_abs_2509_14357
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Freeze-Tag is NP-hard in 2D with $L_1$ distance
Silva, Lucas de Oliveira
Pedrosa, Lehilton Lelis Chaves
Computational Geometry
Computational Complexity
The Freeze-Tag Problem (FTP) is a scheduling problem with application in robot swarm activation and was introduced by Arkin et al. in 2002. This problem seeks an efficient way of activating a robot swarm, starting with a single active robot. Activations occur through direct contact, and once a robot becomes active, it can move and help activate other robots. Although the problem has been shown to be NP-hard in the Euclidean plane $\mathbb{R}^2$ under the $L_2$ distance, and in three-dimensional Euclidean space $\mathbb{R}^3$ under any $L_p$ distance with $p \ge 1$, its complexity under the $L_1$ (Manhattan) distance in $\mathbb{R}^2$ has remained an open question. In this paper, we settle this question by proving that FTP is strongly NP-hard in the Euclidean plane with $L_1$ distance.
title Freeze-Tag is NP-hard in 2D with $L_1$ distance
topic Computational Geometry
Computational Complexity
url https://arxiv.org/abs/2509.14357