A farmer wants to get his goat, wolf and cabbage
to other side of the river. His boat is only big enough to carry him
and either his goat, his wolf or his cabbage. If he leaves the goat
alone with the cabbage, the goat will eat the cabbage. If he leaves
the wolf with the goat, the wolf will eat the goat. Only when the
farmer is present are the goat and the cabbage safe from their
predators. How does he manage to get everything to the other side?