Editing Boy's surface (section)

=== Model at Oberwolfach ===
The [[Oberwolfach Research Institute for Mathematics]] has a large model of a Boy's surface outside the entrance, constructed and donated by [[Mercedes-Benz]] in January 1991. This model has 3-fold [[rotational symmetry]] and minimizes the [[Willmore energy]] of the surface. It consists of steel strips representing the image of a [[Polar coordinate system|polar coordinate grid]] under a parameterization given by Robert Bryant and Rob Kusner. The meridians (rays) become ordinary [[Möbius strip]]s, i.e. twisted by 180 degrees. All but one of the strips corresponding to circles of latitude (radial circles around the origin) are untwisted, while the one corresponding to the boundary of the unit circle is a Möbius strip twisted by three times 180 degrees &mdash; as is the emblem of the institute {{harv|Mathematisches Forschungsinstitut Oberwolfach|2011}}.