Theoretical Computer Science
The complexity of searching a graph
Journal of the ACM (JACM)
Min cut is NP-complete for edge weighted trees
Theoretical Computer Science - Thirteenth International Colloquim on Automata, Languages and Programming, Renne
Recontamination does not help to search a graph
Journal of the ACM (JACM)
The vertex separation and search number of a graph
Information and Computation
Distributed loop computer networks: a survey
Journal of Parallel and Distributed Computing
Optimal distributed algorithms in unlabeled tori and chordal rings
Journal of Parallel and Distributed Computing
Intrusion detection using autonomous agents
Computer Networks: The International Journal of Computer and Telecommunications Networking - Special issue on recent advances in intrusion detection systems
Capture of an intruder by mobile agents
Proceedings of the fourteenth annual ACM symposium on Parallel algorithms and architectures
Contiguous Search in the Hypercube for Capturing an Intruder
IPDPS '05 Proceedings of the 19th IEEE International Parallel and Distributed Processing Symposium (IPDPS'05) - Papers - Volume 01
Distributed chasing of network intruders
Theoretical Computer Science
Theoretical Computer Science
Distributed security algorithms by mobile agents
ICDCN'06 Proceedings of the 8th international conference on Distributed Computing and Networking
Distributed chasing of network intruders
SIROCCO'06 Proceedings of the 13th international conference on Structural Information and Communication Complexity
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In this paper we consider the problem of decontaminating a network, i.e., protecting it from unwanted and dangerous intrusions. Initially all nodes are contaminated and a team of agents is deployed to clean the entire network. When an agent transits on a node, it can clean it, when the node is left unguarded, however, it will be recontaminated as soon as at least one of its neighbour is contaminated. We study the problem in asynchronous chordal ring networks with n nodes and chord lengths d1 = 1, d2, ..., dk, and in tori. We consider two variations of the model: one where an agent has only local knowledge, the other in which it has "visibility", i.e., it can "see" the state of its neighbouring nodes. We first show that, when the largest chord dk is not too large (dk ≤ √n), the number of agents necessary to perform the task in chordal rings does not depend on the size of the network but only on the length of the longest chord. We also show a lower bound on the number of agents for the torus topology. We then propose tight strategies for decontamination. We analyse the number of moves and the time complexity of the decontamination algorithms showing that the visibility assumption allows us to decrease substantially both complexity measures. Another advantage of the "visibility model" is that agents move independently and autonomously without requiring any coordination.