(parallel) Chip firing works as follows. You put some chips on the vertices
of a graph. After one second, each vertex decides whether it is active or
passive. It is active (indicated by the red frame) if it has at least as many
chips as neighbors. If it is active, it sends one chip to each of its neighbors.
If it is passive, it does nothing. The same process is repeated after two
seconds, after three seconds, and so on. Eventually, we get periodic patterns.
Try chip firing on the cube when starting with
random distributions. Check what periods are possible for different number
Try chip firing on different graphs.