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Two-Agent Tree Evacuation

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Structural Information and Communication Complexity (SIROCCO 2021)

Part of the book series: Lecture Notes in Computer Science ((LNTCS,volume 12810))

Abstract

We study the problem of evacuating two agents from a tree graph, through an unknown exit located at one of the nodes. Initially, the agents are located at the same starting node; they explore the graph until one of them finds the exit through which they can evacuate. The task is to minimize the time it takes until both agents evacuate, for a worst case placement of the exit. We consider two communication models, global communication where the agents can communicate at any time, and local communication where the agents can only communicate if they are at the same node at the same time. We show that the problem is NP-hard in both cases. We then present a 4/3-approximation algorithm for global and a 3/2-approximation algorithm for local communication.

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Acknowledgements

We would like to thank Nicolas Marxer and Tobias Zwahlen for fruitful discussions and the anonymous reviewers for their helpful comments.

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Authors and Affiliations

  1. ETH Zürich, Zürich, Switzerland

    Henri Devillez, Béni Egressy, Robin Fritsch & Roger Wattenhofer

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  1. Henri Devillez
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  2. Béni Egressy
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  3. Robin Fritsch
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  4. Roger Wattenhofer
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Corresponding author

Correspondence to Béni Egressy .

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Editors and Affiliations

  1. Institute of Computer Science, University of Wrocław, Wroclaw, Poland

    Tomasz Jurdziński

  2. University of Vienna, Vienna, Austria

    Stefan Schmid

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Devillez, H., Egressy, B., Fritsch, R., Wattenhofer, R. (2021). Two-Agent Tree Evacuation. In: Jurdziński, T., Schmid, S. (eds) Structural Information and Communication Complexity. SIROCCO 2021. Lecture Notes in Computer Science(), vol 12810. Springer, Cham. https://doi.org/10.1007/978-3-030-79527-6_12

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  • DOI: https://doi.org/10.1007/978-3-030-79527-6_12

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  • Print ISBN: 978-3-030-79526-9

  • Online ISBN: 978-3-030-79527-6

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