Bad actors in this context refer to participants that become unavailable due to various reasons, such as crashes, high response latency, removal by human intervention, or deliberate non-responsiveness when certain constraints are not met (e.g., lacking an up-to-date state).

In a system with 'f' bad actors, we need at least 'f+1' good actors to ensure that the system as a whole remains good. This means the total number of actors in the system is '2f + 1'.