Timeline for What is geometrically the Pontryagin class?
Current License: CC BY-SA 3.0
13 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 10, 2015 at 9:39 | answer | added | მამუკა ჯიბლაძე | timeline score: 7 | |
| Feb 10, 2015 at 7:37 | answer | added | András Szűcs | timeline score: 2 | |
| Sep 17, 2013 at 11:22 | vote | accept | ARG | ||
| Sep 8, 2013 at 12:39 | answer | added | András Szűcs | timeline score: 32 | |
| Dec 23, 2012 at 15:30 | comment | added | Paul Siegel | Perhaps you are already aware of this, but generally one obtains interesting invariants as polynomials in the pontryagin classes rather than by looking at the pontryagin classes themselves - see the A-hat genus or the hirzebruch L-class, for instance. | |
| Dec 23, 2012 at 10:06 | history | edited | ARG | CC BY-SA 3.0 |
"deleted" mistake
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| Dec 23, 2012 at 10:05 | comment | added | ARG | @Charles: I would also like to hear about this if you ever get the answer. @Paul: thanks, but I was more looking to learn what is the system of generator $\langle \alpha, \beta \rangle$ of $\mathbb{Z} \times \mathbb{Z}$ so that given an element, if one writes it down as $a \alpha + b \beta$ then $a$ would be associated to the Euler class and $b$ to the Pontryagin class | |
| Dec 22, 2012 at 23:19 | comment | added | Paul | $SO(4)$ is double covered by $SU(2)\times SU(2)$ and since $SU(2)=S^3$, $\pi_3(SO(4))=\pi_3(S^3)\times \pi_3S^3=Z\times Z$. | |
| Dec 22, 2012 at 20:01 | comment | added | Charles Rezk | A related question (which I don't know the answer to): What was Pontryagin's motivation for introducing theses classes? (And if it wasn't him, who did introduce them, why?) | |
| Dec 22, 2012 at 19:42 | answer | added | Henry T. Horton | timeline score: 18 | |
| Dec 22, 2012 at 18:13 | answer | added | Alexander Chervov | timeline score: 10 | |
| Dec 22, 2012 at 18:00 | answer | added | Liviu Nicolaescu | timeline score: 11 | |
| Dec 22, 2012 at 17:13 | history | asked | ARG | CC BY-SA 3.0 |