If M’s a complete metric space,
And non-empty, it’s always the case,
If f’s a contraction,
Then under its action,
Exactly one point stays in place!
A mathematician confided
That a Moebius* strip is one sided
And you get quite a laugh
When you cut it in half:
In stays in one piece when divided.
The topologist’s child was quite hyper
Till she wore a Moebius diaper.
The mess on the inside
Was thus on the outside:
It was easy for someone to wipe her.
(From: Wikipedia – mathematical joke)