Möbius

Although largely forgotten today, Listing is also notable for writing about the Möbius band four years before August Möbius, and for coining the very term topologie.

Like the Möbius strip, it only has one side, and you can actually make one by gluing together two Möbius strips.

Well, two Möbius strips that intersect each other are equivalent to a Klein bottle, which intersects itself in this type of space.

One of the first big ingredients of their proof appeared in November 2019 when a Princeton graduate student named Cole Hugelmeyer posted a paper that introduced a new way of analyzing Vaughan’s Möbius strip.