### Abstract

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 language | English (US) |
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Pages (from-to) | 67-80 |

Number of pages | 14 |

Journal | Lecture Notes in Computer Science |

Volume | 3544 |

Publication status | Published - Oct 17 2005 |

Externally published | Yes |

Event | 8th International Conference on Principles of Distributed Systems, OPODIS 2004 - Grenoble, France Duration: Dec 15 2004 → Dec 17 2004 |

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### Keywords

- Algorithm
- Black hole
- Mobile agent
- Tree

### ASJC Scopus subject areas

- Theoretical Computer Science
- Computer Science(all)

### Cite this

*Lecture Notes in Computer Science*,

*3544*, 67-80.