Agreement in directed dynamic networks

Martin Biely, Peter Robinson, Ulrich Schmid

Research output: Chapter in Book/Report/Conference proceedingConference contribution

25 Scopus citations


We study the fundamental problem of achieving consensus in a synchronous dynamic network, where an omniscient adversary controls the unidirectional communication links. Its behavior is modeled as a sequence of directed graphs representing the active (i.e. timely) communication links per round. We prove that consensus is impossible under some natural weak connectivity assumptions, and introduce vertex-stable root components as a-practical and not overly strong-means for circumventing this impossibility. Essentially, we assume that there is a short period of time during which an arbitrary part of the network remains strongly connected, while its interconnect topology keeps changing continuously. We present a consensus algorithm that works under this assumption, and prove its correctness. Our algorithm maintains a local estimate of the communication graphs, and applies techniques for detecting stable network properties and univalent system configurations. Our possibility results are complemented by several impossibility results and lower bounds, which reveal that our algorithm is asymptotically optimal.

Original languageEnglish (US)
Title of host publicationStructural Information and Communication Complexity - 19th International Colloquium, SIROCCO 2012, Proceedings
Number of pages12
StatePublished - 2012
Externally publishedYes
Event19th International Colloquium on Structural Information and Communication Complexity, SIROCCO 2012 - Reykjavik, Iceland
Duration: Jun 30 2012Jul 2 2012

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume7355 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference19th International Colloquium on Structural Information and Communication Complexity, SIROCCO 2012

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)


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