TY - GEN

T1 - Brief announcement

T2 - 2012 ACM Symposium on Principles of Distributed Computing, PODC'12

AU - Casteigts, Arnaud

AU - Flocchini, Paola

AU - Godard, Emmanuel

AU - Santoro, Nicola

AU - Yamashita, Masafumi

PY - 2012/8/20

Y1 - 2012/8/20

N2 - We consider infrastructure-less highly dynamic networks, where connectivity does not necessarily hold, and the network may actually be disconnected at every time instant. These networks are naturally modeled as time-varying graphs. Clearly the task of designing protocols for these networks is less difficult if the environment allows waiting (i.e., it provides the nodes with store-carry-forward-like mechanisms such as local buffering) than if waiting is not feasible. We provide a quantitative corroboration of this fact in terms of the expressivity of the corresponding time-varying graph; that is in terms of the language generated by the feasible journeys in the graph. We prove that the set of languages L nowait when no waiting is allowed contains all computable languages. On the other end, we prove that L wait is just the family of regular languages. This gap is a measure of the computational power of waiting. We also study bounded waiting; that is when waiting is allowed at a node only for at most d time units. We prove the negative result that L wait[d] = L nowait.

AB - We consider infrastructure-less highly dynamic networks, where connectivity does not necessarily hold, and the network may actually be disconnected at every time instant. These networks are naturally modeled as time-varying graphs. Clearly the task of designing protocols for these networks is less difficult if the environment allows waiting (i.e., it provides the nodes with store-carry-forward-like mechanisms such as local buffering) than if waiting is not feasible. We provide a quantitative corroboration of this fact in terms of the expressivity of the corresponding time-varying graph; that is in terms of the language generated by the feasible journeys in the graph. We prove that the set of languages L nowait when no waiting is allowed contains all computable languages. On the other end, we prove that L wait is just the family of regular languages. This gap is a measure of the computational power of waiting. We also study bounded waiting; that is when waiting is allowed at a node only for at most d time units. We prove the negative result that L wait[d] = L nowait.

UR - http://www.scopus.com/inward/record.url?scp=84864973692&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84864973692&partnerID=8YFLogxK

U2 - 10.1145/2332432.2332452

DO - 10.1145/2332432.2332452

M3 - Conference contribution

AN - SCOPUS:84864973692

SN - 9781450314503

T3 - Proceedings of the Annual ACM Symposium on Principles of Distributed Computing

SP - 99

EP - 100

BT - PODC'12 - Proceedings of the 2012 ACM Symposium on Principles of Distributed Computing

Y2 - 16 July 2012 through 18 July 2012

ER -