ILCINKAS, David; WADE, Ahmed

doi:10.1007/978-3-642-25873-2_31

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ILCINKAS, David
Laboratoire Bordelais de Recherche en Informatique [LaBRI]
Algorithmics for computationally intensive applications over wide scale distributed platforms [CEPAGE]

WADE, Ahmed
Laboratoire Bordelais de Recherche en Informatique [LaBRI]
Algorithmics for computationally intensive applications over wide scale distributed platforms [CEPAGE]

Langue

Communication dans un congrès

Ce document a été publié dans

Proceedings of the 15th International Conference On Principles Of Distributed Systems, Proceedings of the 15th International Conference On Principles Of Distributed Systems, OPODIS 2011, 2011-12-13, Toulouse. 2011, vol. 7109, p. 451-464

Springer Berlin / Heidelberg

Résumé en anglais

We study the problem of exploration by a mobile entity (agent) of a class of dynamic networks, namely the periodically-varying graphs (the PV-graphs, modeling public transportation systems, among others). These are defined by a set of carriers following infinitely their prescribed route along the stations of the network. Flocchini, Mans, and Santoro (ISAAC 2009) studied this problem in the case when the agent must always travel on the carriers and thus cannot wait on a station. They described the necessary and sufficient conditions for the problem to be solvable and proved that the optimal number of steps (and thus of moves) to explore a n-node PV-graph of k carriers and maximal period p is in Theta(k p^2) in the general case. In this paper, we study the impact of the ability to wait at the stations. We exhibit the necessary and sufficient conditions for the problem to be solvable in this context, and we prove that waiting at the stations allows the agent to reduce the worst-case optimal number of moves by a multiplicative factor of at least Theta(p), while the time complexity is reduced to Theta(n p). (In any connected PV-graph, we have n < k p$.) We also show some complementary optimal results in specific cases (same period for all carriers, highly connected PV-graphs). Finally this new ability allows the agent to completely map the PV-graph, in addition to just explore it.< Réduire

Mots clés

Exploration

Dynamic graphs

Mobile agent

PV-graph

URI

https://oskar-bordeaux.fr/handle/20.500.12278/197957

DOI

http://dx.doi.org/10.1007/978-3-642-25873-2_31

Project ANR

Algorithm Design and Analysis for Implicitly and Incompletely Defined Interaction Networks - ANR-07-BLAN-0322

Origine

Importé de hal

Unités de recherche

Laboratoire Bordelais de Recherche en Informatique (LaBRI) - UMR 5800