It is well known that the failure detector Ω is necessary and sufficient to solve consensus in asynchronous message passing systems where a majority of processes is guaranteed to be correct [1,2]. But what if the problem were to be solved in an arbitrary environment where any number of processes may fail and at any times? The answer was provided by Delporte et al who showed that a certain quorum failure detector, which they called Σ, is necessary and, together with Ω, sufficient to solve consensus in any environment [4].