The Byzantine generals problem considers a computer with many programs running, some of them possibly unfriendly, and asks how the computer can function properly.
More abstractly, consider a group of generals of the Byzantine army around a city. Communicating only by messenger, the generals must agree upon a common battle plan.
However, one or more of them may be traitors who will try to confuse the others.
Analysis and solutions of the problem are given by Lamport et al. (1982).
