Imagine that you're a supercomputer. Now imagine that you're bored. So you dream up a little contest for you and a couple of your supercomputing buddies. Your task is to move one of the stupid little robots out on the factory floor through a series of checkpoints scattered throughout the factory.
The wrinkle, however, is that the factory floor is filled with all kinds of inconvenient (if not down-right deadly) obstacles located in various locations: conveyor belts, crushers, flame-throwers, pushers, teleporters, oil slicks, pits, et cetera.
But the real fun comes when the robots cross each other's path, and suddenly your perfect route is something less than that...