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Main Authors: Di Luna, Giuseppe Antonio, Flocchini, Paola, Prencipe, Giuseppe, Santoro, Nicola
Format: Preprint
Published: 2024
Subjects:
Online Access:https://arxiv.org/abs/2404.15132
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author Di Luna, Giuseppe Antonio
Flocchini, Paola
Prencipe, Giuseppe
Santoro, Nicola
author_facet Di Luna, Giuseppe Antonio
Flocchini, Paola
Prencipe, Giuseppe
Santoro, Nicola
contents In this paper, we address the challenge of locating a black hole within a dynamic graph using a set of scattered agents, which start from arbitrary positions in the graph. A black hole is defined as a node that silently eliminates any agent that visits it, effectively modeling network failures such as a crashed host or a destructive virus. The black hole search problem is considered solved when at least one agent survives and possesses a complete map of the graph, including the precise location of the black hole. Our study focuses on the scenario where the underlying graph is a dynamic 1-interval connected ring: a ring graph where, in each round, one edge may be absent. Agents communicate with other agents using movable pebbles that can be placed on nodes. In this setting, we demonstrate that three agents are sufficient to identify the black hole in $O(n^2)$ moves. Furthermore, we prove that this number of agents is optimal. Additionally, we establish that the complexity bound is tight, requiring $Ω(n^2)$ moves for any algorithm solving the problem with three agents, even when stronger communication mechanisms, such as unlimited-size whiteboards on nodes, are available.
format Preprint
id arxiv_https___arxiv_org_abs_2404_15132
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Black Hole Search by Scattered Agents in Dynamic Rings
Di Luna, Giuseppe Antonio
Flocchini, Paola
Prencipe, Giuseppe
Santoro, Nicola
Distributed, Parallel, and Cluster Computing
In this paper, we address the challenge of locating a black hole within a dynamic graph using a set of scattered agents, which start from arbitrary positions in the graph. A black hole is defined as a node that silently eliminates any agent that visits it, effectively modeling network failures such as a crashed host or a destructive virus. The black hole search problem is considered solved when at least one agent survives and possesses a complete map of the graph, including the precise location of the black hole. Our study focuses on the scenario where the underlying graph is a dynamic 1-interval connected ring: a ring graph where, in each round, one edge may be absent. Agents communicate with other agents using movable pebbles that can be placed on nodes. In this setting, we demonstrate that three agents are sufficient to identify the black hole in $O(n^2)$ moves. Furthermore, we prove that this number of agents is optimal. Additionally, we establish that the complexity bound is tight, requiring $Ω(n^2)$ moves for any algorithm solving the problem with three agents, even when stronger communication mechanisms, such as unlimited-size whiteboards on nodes, are available.
title Black Hole Search by Scattered Agents in Dynamic Rings
topic Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2404.15132