4 ms·
Thank you for the correction I actually didn't realise that so have learned something. Specifically for people who are interested it seems you have to replace
by seanhunter 6mo ago
Thank you for the correction I actually didn't realise that so have learned something.
Specifically for people who are interested it seems you have to replace the parallel postulate with a postulate that says every point is a saddle point (which is like the centre point of a pringle if you know what that looks like).
https://en.wikipedia.org/wiki/Pringles https://en.wikipedia.org/wiki/Pringles
- lmm 6mo agoYou can also replace it with a different postulate and get projective geometry, IIRC.