Piecemeal graph exploration by a mobile robot
Information and Computation
Exploring Unknown Environments
SIAM Journal on Computing
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Journal of Computer and System Sciences - Special issue on STOC 2000
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Optimal graph exploration without good maps
Theoretical Computer Science
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Proceedings of the 2005 ACM SIGCOMM workshop on Delay-tolerant networking
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DIALM-POMC '05 Proceedings of the 2005 joint workshop on Foundations of mobile computing
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CoNEXT '07 Proceedings of the 2007 ACM CoNEXT conference
Journal of Graph Theory
Label-guided graph exploration by a finite automaton
ACM Transactions on Algorithms (TALG)
How to Explore a Fast-Changing World (Cover Time of a Simple Random Walk on Evolving Graphs)
ICALP '08 Proceedings of the 35th international colloquium on Automata, Languages and Programming, Part I
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IEEE Transactions on Parallel and Distributed Systems
The Deep Impact Network Experiment Operations Center Monitor and Control System
SMC-IT '09 Proceedings of the Third IEEE International Conference on Space Mission Challenges for Information Technology
Proceedings of the 4th ACM workshop on Challenged networks
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ISAAC '09 Proceedings of the 20th International Symposium on Algorithms and Computation
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IEEE Transactions on Information Theory
Routing in carrier-based mobile networks
SIROCCO'11 Proceedings of the 18th international conference on Structural information and communication complexity
Measuring Temporal Lags in Delay-Tolerant Networks
IPDPS '11 Proceedings of the 2011 IEEE International Parallel & Distributed Processing Symposium
Flooding Time of Edge-Markovian Evolving Graphs
SIAM Journal on Discrete Mathematics
Searching for Black Holes in Subways
Theory of Computing Systems - Special Issue: Fun with Algorithms
Characterizing topological assumptions of distributed algorithms in dynamic networks
SIROCCO'09 Proceedings of the 16th international conference on Structural Information and Communication Complexity
On the power of waiting when exploring public transportation systems
OPODIS'11 Proceedings of the 15th international conference on Principles of Distributed Systems
IEEE Communications Surveys & Tutorials
Building a reference combinatorial model for MANETs
IEEE Network: The Magazine of Global Internetworking
Time-varying graphs and dynamic networks
International Journal of Parallel, Emergent and Distributed Systems
Expressivity of time-varying graphs
FCT'13 Proceedings of the 19th international conference on Fundamentals of Computation Theory
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We study the computability and complexity of the exploration problem in a class of highly dynamic networks: carrier graphs, where the edges between sites exist only at some (unknown) times defined by the periodic movements of mobile carriers among the sites. These graphs naturally model highly dynamic infrastructure-less networks such as public transports with fixed timetables, low earth orbiting (LEO) satellite systems, security guards' tours, etc. We focus on the opportunistic exploration of these graphs, that is by an agent that exploits the movements of the carriers to move in the network. We establish necessary conditions for the problem to be solved. We also derive lower bounds on the amount of time required in general, as well as for the carrier graphs defined by restricted classes of carrier movements. We then prove that the limitations on computability and complexity we have established are indeed tight. In fact we prove that all necessary conditions are also sufficient and all lower bounds on costs are tight. We do so constructively by presenting two optimal solution algorithms, one for anonymous systems, and one for those with distinct node IDs.