The old joke that mathematicians can't distinguish a donut from a coffee mug (because of topological "equivalence"/homeomorphism) [0] [0] https://en.wikipedia.

The old joke that mathematicians can't distinguish a donut from a coffee mug (because of topological "equivalence"/homeomorphism) [0] [0] https://en.wikipedia.org/wiki/File:Mug_and_Torus_morph.gif https://en.wikipedia.org/wiki/File:Mug_and_Torus_morph.gif