A biologist, a statistician, a mathematician and a computer
scientist are on a photo-safari in africa. They drive out on the
savannah in their jeep, stop and scout the horizon with
their binoculars.
The biologist : "Look! There's a herd of zebras! And there,
in the middle : A white zebra! It's fantastic !
There are white zebra's ! We'll be famous !"
The statistician : "It's not significant. We only know there's one
white zebra."
The mathematician : "Actually, we only know there exists a zebra,
which is white on one side."
The computer scientist : "Oh, no! A special case!"
