An engineer, a physicist, and a mathematician...

An engineer, a physicist, and a mathematician are shown a pasture with
a herd of sheep, and told to put them inside the smallest possible
amount of fence.


The engineer is first. He herds the sheep into a
circle and
then puts the fence around them, declaring, "A circle will use the least
fence for a given area, so this is the best solution."


The physicist is
next. She creates a circular fence of infinite radius around the sheep,
and then draws the fence tight around the herd, declaring, "This will
give the
smallest circular fence around the herd."


The mathematician is last.
After
giving the problem a little thought, he puts a small fence around
himself and then declares, "I define myself to be on the outside!"