Jean-Claude Matthys recommande la vidéo
The Klein Bottle is a surface on which you can move from outside to inside without crossing an edge. This shows that inside and outside are not universal concepts.
In this movie Klein’s Bottle is constructed by gluing an rectangle along the edges. Then the bottle is cut up again to yield a Moebius-strip.
This Video was produces for a topology seminar at the Leibniz Universitaet Hannover.