In this paper, we prove that to solve Consensus, any failure detector has to provide at least as much information as 3W. Thus, 3W is indeed the weakest failure detector for solving Consensus in asynchronous systems with a majority of correct processes.
Processes can fail by crashing, and links can fail by dropping messages.
The weakest failure detector for solving consensus. Technical report, Computer Systems Research Intitute, Univ. of Toronto, and Dept. of Computer Science, Cornell Univ., May 1994. Doc 80 Consensus in the presence of partial synchrony - Dwork, Lynch et al. Doc 47 Reaching approximate agreement in the presence of faults - Dolev, Lynch et al. The graph only includes citing articles where the year of publication is known.