Self-stabilizing Graph Exploration by a Single Agent

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Hauptverfasser: Sudo, Yuichi, Ooshita, Fukuhito, Kamei, Sayaka
Format: Preprint
Veröffentlicht: 2020
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author Sudo, Yuichi
Ooshita, Fukuhito
Kamei, Sayaka
author_facet Sudo, Yuichi
Ooshita, Fukuhito
Kamei, Sayaka
contents In this paper, we present two self-stabilizing algorithms that enable a single (mobile) agent to explore graphs. Starting from any initial configuration, \ie regardless of the initial states of the agent and all nodes, as well as the initial location of the agent, the algorithms ensure the agent visits all nodes. We evaluate the algorithms based on two metrics: the \emph{cover time}, defined as the number of moves required to visit all nodes, and \emph{memory usage}, defined as the storage needed for maintaining the states of the agent and each node. The first algorithm is randomized. Given an integer $c = Ω(n)$, its cover time is optimal, \ie $O(m)$ in expectation, and its memory requirements are $O(\log c)$ bits for the agent and $O(\log (c+δ_v))$ bits for each node $v$, where $n$ and $m$ are the numbers of nodes and edges, respectively, and $δ_v$ is the degree of node $v$. For general $c \ge 2$, its cover time is $O( m \cdot \min(D, \frac{n}{c}+1, \frac{D}{c} + \log n))$, where $D$ is the diameter of a graph. The second algorithm is deterministic. It requires an input integer $k \ge \max(D, \dmax)$, where $\dmax$ is the maximum degree of the graph. The cover time of this algorithm is $O(m + nD)$, and it uses $O(\log k)$ bits of memory for both the agent and each node.
format Preprint
id arxiv_https___arxiv_org_abs_2010_08929
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Self-stabilizing Graph Exploration by a Single Agent
Sudo, Yuichi
Ooshita, Fukuhito
Kamei, Sayaka
Distributed, Parallel, and Cluster Computing
In this paper, we present two self-stabilizing algorithms that enable a single (mobile) agent to explore graphs. Starting from any initial configuration, \ie regardless of the initial states of the agent and all nodes, as well as the initial location of the agent, the algorithms ensure the agent visits all nodes. We evaluate the algorithms based on two metrics: the \emph{cover time}, defined as the number of moves required to visit all nodes, and \emph{memory usage}, defined as the storage needed for maintaining the states of the agent and each node. The first algorithm is randomized. Given an integer $c = Ω(n)$, its cover time is optimal, \ie $O(m)$ in expectation, and its memory requirements are $O(\log c)$ bits for the agent and $O(\log (c+δ_v))$ bits for each node $v$, where $n$ and $m$ are the numbers of nodes and edges, respectively, and $δ_v$ is the degree of node $v$. For general $c \ge 2$, its cover time is $O( m \cdot \min(D, \frac{n}{c}+1, \frac{D}{c} + \log n))$, where $D$ is the diameter of a graph. The second algorithm is deterministic. It requires an input integer $k \ge \max(D, \dmax)$, where $\dmax$ is the maximum degree of the graph. The cover time of this algorithm is $O(m + nD)$, and it uses $O(\log k)$ bits of memory for both the agent and each node.
title Self-stabilizing Graph Exploration by a Single Agent
topic Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2010.08929