Timeline for "Slap your forehead" moments- Greatest Hits
Current License: CC BY-SA 2.5
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 20, 2010 at 7:44 | comment | added | Greg Kuperberg | @Victor Yes, I suppose I did not answer that part of the question. 2 is from a failed proof of the Kepler conjecture, not exactly a pretty proof but at least a proof. 3 shows up from time to time in function field problems. | |
| Jul 17, 2010 at 19:25 | comment | added | Victor Protsak | But where are the pretty proofs that go away? | |
| Jul 17, 2010 at 13:28 | comment | added | Greg Kuperberg | 3. $F = \mathbb{C}(x)$, $K = \mathbb{C}(x^2)$, $L = \mathbb{C}((x+1)^2)$. Actually there are tons of examples in function field theory. 4. $S^1 \times C_2$, $O(2)$, and (the one that is the easiest to miss) $\text{Pin}^-(2)$, the normalizer of a circle in $\text{SU}(2)$. | |
| Jul 17, 2010 at 13:17 | comment | added | Anweshi | What would be a counterexamples for 3? In 4, what is the second Lie group that is diffeomorphic to pair of circles? (the first one is the direct sum of S^1 and Z/2, I assume.) | |
| Jul 17, 2010 at 4:02 | history | answered | Greg Kuperberg | CC BY-SA 2.5 |