Fault-Tolerant Consensus in Unknown and Anonymous Networks

This paper investigates under which conditions information can be reliably shared and consensus can be solved in unknown and anonymous message-passing networks that suffer from crash-failures. We provide algorithms to emulate registers and solve consensus under different synchrony assumptions. For this, we introduce a novel pseudo leader-election approach which allows a leader-based consensus implementation without breaking symmetry

Transforming Asynchronous Systems with Crash-Stop Failures and Failure Detectors to the General Omission Model

This paper studies the impact of omission failures on asynchronous distributed s ystems with crash-stop failures. For the large group of problem specifications that are restricted to correct processes, we show how to transform a crash-stop related problem specification into an equivalent omission one. For that, we provide transformations for algorithms and failure detectors, such that if and only if an algorithm using a failure detector satisfies a problem specification, then the transformed algorithm using the transformed failure detector satisfies the transformed problem specification. Our transformed problem specification is ensured to be non-trivial, and moreover, the transformation reveals itself to be in a reasonable sense weakest failure detector preserving. Our results help to use the power of the well-understood crash-stop model to aut omatically derive solutions for the general omission model, which has recently raised interest for being noticeably applicable for security problems in distributed environments equipped with security modules such as smartcards

The Weakest Failure Detector for Message Passing Set-Agreement

In the set-agreement problem, n processes seek to agree on at most n−1 different values. This paper determines the weakest failure detector to solve this problem in a message-passing system where processes may fail by crashing. This failure detector, called the Loneliness detector and denoted L, outputs one of two values, “true” or “false” such that: (1) there is at least one process where L outputs always “false”, and (2) if only one process is correct, L eventually outputs “true” at this process