Pavel Klavík, A. Cristiano I. Malossi, et al.
Philos. Trans. R. Soc. A
We determine what information about failures is necessary and sufficient to solve Consensus in asynchronous distributed systems subject to crash failures. In Chandra and Toueg [1996] it is shown that ◇script W sign, a failure detector that provides surprisingly little information about which processes have crashed, is sufficient to solve Consensus in asynchronous systems with a majority of correct processes. In this paper, we prove that to solve Consensus, any failure detector has to provide at least as much information as ◇script W sign. Thus, ◇script W sign is indeed the weakest failure detector for solving Consensus in asynchronous systems with a majority of correct processes.