Black Hole Search in Asynchronous Rings Using Tokens

  • S. Dobrev
  • R. Královič
  • N. Santoro
  • W. Shi
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3998)


A black hole is a highly harmful host that disposes of visiting agents upon their arrival. It is known that it is possible for a team of mobile agents to locate a black hole in an asynchronous ring network if each node is equipped with a whiteboard of at least O(log n) dedicated bits of storage. In this paper, we consider the less powerful token model: each agent has has available a bounded number of tokens that can be carried, placed on a node or removed from it. All tokens are identical (i.e., indistinguishable) and no other form of communication or coordination is available to the agents. We first of all prove that a team of two agents is sufficient to locate the black hole in finite time even in this weaker coordination model. Furthermore, we prove that this can be accomplished using only O(n log n) moves in total, which is optimal, the same as with whiteboards. Finally, we show that to achieve this result the agents need to use only O(1) tokens each.


Black Hole Mobile Agent Work Assignment Asynchronous System Unexplored Region 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • S. Dobrev
    • 1
  • R. Královič
    • 2
  • N. Santoro
    • 3
  • W. Shi
    • 3
  1. 1.School of Information Technology and EngineeringUniversity of OttawaOttawaCanada
  2. 2.Dept. of Computer ScienceComenius UniversityBratislavaSlovakia
  3. 3.School of Computer ScienceCarleton UniversityOttawaCanada

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