Showing papers on "Consensus published in 1987"
TL;DR: The proofs expose general heuristic principles that explain why consensus is possible in certain models but not possible in others, and several critical system parameters, including various synchronicity conditions, are identified.
Abstract: Reaching agreement is a primitive of distributed computing. Whereas this poses no problem in an ideal, failure-free environment, it imposes certain constraints on the capabilities of an actual system: A system is viable only if it permits the existence of consensus protocols tolerant to some number of failures. Fischer et al. have shown that in a completely asynchronous model, even one failure cannot be tolerated. In this paper their work is extended: Several critical system parameters, including various synchrony conditions, are identified and how varying these affects the number of faults that can be tolerated is examined. The proofs expose general heuristic principles that explain why consensus is possible in certain models but not possible in others.
743 citations
TL;DR: It is proved that a large class of distributed tasks cannot be solved in the presence of faulty processors, and the notion of the decision graph of a task is introduced, and it is shown that every problem whose decision graph is disconnected cannot be unsolved by reducing the unsolvability of this problem to the unsoliability of the consensus problem.
100 citations
TL;DR: It is shown that, with nonzero probability, a protocol can achieve consensus even during executions where the number of actual processors to fail exceeds its resiliency.
6 citations
01 Dec 1987
TL;DR: In this paper, the authors developed additional results on the problem of reaching a consensus of opinion between two decisionmakers provided with different information, and they showed that incorporating human uncertainty in probability assessment into the asymptotic agreement problem can lead to outcomes not anticipated in the general theory.
Abstract: In this paper, we develop additional results on the problem of reaching a consensus of opinion between two decisionmakers provided with different information. Specifically, we study the problem where the two decisionmakers may have different underlying probability models. We develop results characterizing the likelihood of an agreement being reached eventually in terms of the nature of the inter-decisionmaker communications. We also study the problem when the decisionmakers are aware of the possibility that they may have different models. In this case, the decisionmakers can reach a deadlock state where neither decisionmaker can learn additional information from the consensus process, and they cannot reach a consensus decision. This surprising result indicates that incorporating human uncertainty in probability assessment into the asymptotic agreement problem can lead to outcomes not anticipated in the general theory previously developed.
3 citations
TL;DR: This paper is aimed at reviewing the notion of Byzantine-resilient distributed computing systems, the relevant protocols and their possible applications as reported in the literature and various agreement protocols for the Byzantine generals problem are summarized in terms of their performance and level of fault-tolerance.
Abstract: This paper is aimed at reviewing the notion of Byzantine-resilient distributed computing systems, the relevant protocols and their possible applications as reported in the literature. The three agreement problems, namely, the consensus problem, the interactive consistency problem, and the generals problem have been discussed. Various agreement protocols for the Byzantine generals problem have been summarized in terms of their performance and level of fault-tolerance. The three classes of Byzantine agreement protocols discussed are the deterministic, randomized, and approximate agreement protocols. Finally, application of the Byzantine agreement protocols to clock synchronization is highlighted.
2 citations