real projective plane
The real projective plane is a two-dimensional surface that can be visualized as a disk where opposite edges are identified. This means that if you travel off one edge, you re-enter from the opposite side. It is a non-orientable surface, which means it does not have a consistent "left" or "right" side, similar to a Möbius strip.
In mathematical terms, the real projective plane can be constructed by taking a sphere and identifying antipodal points, meaning that each point on the sphere is paired with the point directly opposite it. This unique property leads to interesting implications in topology and geometry, making it a fundamental object of study in these fields.