Collective tree exploration

Pierre Fraigniaud, Leszek Gasieniec, Dariusz R. Kowalski, Andrzej Pelc

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

An n-node tree has to be explored by k mobile agents (robots), starting in its root. Every edge of the tree must be traversed by at least one robot, and exploration must be completed as fast as possible. Even when the tree is known in advance, scheduling optimal collective exploration turns out to be NP-hard. We investigate the problem of distributed collective exploration of unknown trees. Not surprisingly, communication between robots influences the time of exploration. Our main communication scenario is the following: robots can communicate by writing at the currently visited node previously acquired information, and reading information available at this node. We construct an exploration algorithm whose running time for any tree is only O(k/ log k) larger than optimal exploration time with full knowledge of the tree. (We say that the algorithm has overhead O(k/ log k)). On the other hand we show that, in order to get overhead sublinear in the number of robots, some communication is necessary. Indeed, we prove that if robots cannot communicate at all, then every distributed exploration algorithm works in time Ω(k) larger than optimal exploration time with full knowledge, for some trees.

Original languageEnglish (US)
Title of host publicationLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
EditorsMartin Farach-Colton
PublisherSpringer Verlag
Pages141-151
Number of pages11
ISBN (Print)3540212582, 9783540212584
StatePublished - Jan 1 2004
Externally publishedYes

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume2976
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Fingerprint

Robots
Robot
Communication
Vertex of a graph
Mobile agents
Optimal Scheduling
Mobile Agent
Scheduling
NP-complete problem
Roots
Unknown
Scenarios
Necessary
Knowledge

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)

Cite this

Fraigniaud, P., Gasieniec, L., Kowalski, D. R., & Pelc, A. (2004). Collective tree exploration. In M. Farach-Colton (Ed.), Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (pp. 141-151). (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 2976). Springer Verlag.

Collective tree exploration. / Fraigniaud, Pierre; Gasieniec, Leszek; Kowalski, Dariusz R.; Pelc, Andrzej.

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). ed. / Martin Farach-Colton. Springer Verlag, 2004. p. 141-151 (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 2976).

Research output: Chapter in Book/Report/Conference proceedingChapter

Fraigniaud, P, Gasieniec, L, Kowalski, DR & Pelc, A 2004, Collective tree exploration. in M Farach-Colton (ed.), Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), vol. 2976, Springer Verlag, pp. 141-151.
Fraigniaud P, Gasieniec L, Kowalski DR, Pelc A. Collective tree exploration. In Farach-Colton M, editor, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). Springer Verlag. 2004. p. 141-151. (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)).
Fraigniaud, Pierre ; Gasieniec, Leszek ; Kowalski, Dariusz R. ; Pelc, Andrzej. / Collective tree exploration. Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). editor / Martin Farach-Colton. Springer Verlag, 2004. pp. 141-151 (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)).
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