Searching for a black hole in tree networks

Jurek Czyzowicz, Dariusz Kowalski, Euripides Markou, Andrzej Pelc

Research output: Contribution to journalConference articlepeer-review

11 Scopus citations


A black hole is a highly harmful stationary process residing in a node of a network and destroying all mobile agents visiting the node, without leaving any trace. We consider the task of locating a black hole in a (partially) synchronous tree network, assuming an upper bound on the time of any edge traversal by an agent. The minimum number of agents capable to identify a black hole is two. For a given tree and given starting node we are interested in the fastest possible black hole search by two agents. For arbitrary trees we give a 5/3-approximation algorithm for this problem. We give optimal black hole search algorithms for two "extreme" classes of trees: the class of lines and the class of trees in which any internal node (including the root which is the starting node) has at least 2 children.

Original languageEnglish (US)
Pages (from-to)67-80
Number of pages14
JournalLecture Notes in Computer Science
StatePublished - 2005
Externally publishedYes
Event8th International Conference on Principles of Distributed Systems, OPODIS 2004 - Grenoble, France
Duration: Dec 15 2004Dec 17 2004


  • Algorithm
  • Black hole
  • Mobile agent
  • Tree

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)


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