Add new comment


Quite an impressive review!

Just 2 small correction -

1) There is another compact surface besides the 4 you have mentioned that can be constructed from a flat 2D square. Its constructed by gluing each pair of opposite edges with a 180 degree twist. It's called "Boy's Surface".

2) A 2D Torus T^2 has a only Extrinsic Curvature, but NO Intrinsic Curvature.

Filtered HTML

  • Web page addresses and email addresses turn into links automatically.
  • Allowed HTML tags: <a href hreflang> <em> <strong> <cite> <code> <ul type> <ol start type> <li> <dl> <dt> <dd>
  • Lines and paragraphs break automatically.
  • Want facts and want them fast? Our Maths in a minute series explores key mathematical concepts in just a few words.