Timeline for Computing Slim Extensions representing Ext
Current License: CC BY-SA 3.0
4 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Nov 27, 2012 at 18:37 | comment | added | Joseph Victor | Good point, mt. These are clearly exact. | |
| Nov 27, 2012 at 8:42 | comment | added | M T | $j$ has a kernel equal to $\operatorname{im} \iota$, so $j^{-1}(N)$ contains $\operatorname{im} \iota$ and is never zero. In the case you describe, the sequence splits. | |
| Nov 27, 2012 at 3:26 | comment | added | Joseph Victor | I tried something like this but game up. I don't think these are still exact. Pick some 1-d $N$ which maps onto $k$, then $j^{-1}(N)=0$ but exactness, but $k\to 0$ is not injective. Am I missing something? | |
| Nov 26, 2012 at 9:12 | history | answered | M T | CC BY-SA 3.0 |