Unbeatable Consensus

  • Armando Castañeda
  • Yannai A. Gonczarowski
  • Yoram Moses
Part of the Lecture Notes in Computer Science book series (LNCS, volume 8784)


The unbeatability of a consensus protocol, introduced by Halpern, Moses and Waarts in [15], is a stronger notion of optimality than the accepted notion of early stopping protocols. Using a novel knowledge-based analysis, this paper derives the first practical unbeatable consensus protocols in the literature, for the standard synchronous message-passing model with crash failures. These protocols strictly dominate the best known protocols for uniform and for non-uniform consensus, in some case beating them by a large margin. The analysis provides a new understanding of the logical structure of consensus, and of the distinction between uniform and nonuniform consensus. Finally, the first (early stopping and) unbeatable protocol that treats decision values “fairly” is presented. All of these protocols have very concise descriptions, and are shown to be efficiently implementable.


Consensus uniform consensus optimality knowledge 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Armando Castañeda
    • 1
  • Yannai A. Gonczarowski
    • 2
  • Yoram Moses
    • 3
  1. 1.Universidad Nacional Autónoma de México (UNAM)México
  2. 2.The Hebrew University of Jerusalem and Microsoft ResearchIsrael
  3. 3.Technion — Israel Institute of TechnologyIsrael

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