Cutting a torus
We can cut a torus along a simple, closed curve and it won't divide in two parts.
See also the interactive animation Cutting a surface.
© matematita
immagine di Gian Marco Todesco
The image belongs to the sections...:
From "fragments of topology" (From "XlaTangente")
The torus (Topology)
Images from the topology section (From the exhibitions of matematita)
Further information:
http://www.toonz.com/personal/todesco