Timeline for $\inf\{i\in \mathbb N \cup \{0\}\cup\infty\mid Ext^i_R(R/I,R)\neq 0\}=0 ?$
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| May 12, 2015 at 15:48 | comment | added | user 1 | Fernando Muro is right, but this answer is helpful. | |
| May 2, 2015 at 15:17 | comment | added | John Palmieri | Fred: It could be in this case, though. Take a graded free resolution of $R/I$; this is still free in the ungraded case. I think the only issue is that there will be extra ungraded maps from a graded free module to $R$. I wonder if those can be dealt with in some nice way. | |
| May 2, 2015 at 15:11 | comment | added | John Palmieri | Fernando: you're right, I was misinterpreting the question as asking whether Ext^i was zero for positive i. | |
| May 1, 2015 at 5:18 | comment | added | Fred Rohrer | Graded Ext is not necessarily the same as ungraded Ext! | |
| Apr 30, 2015 at 23:10 | comment | added | Fernando Muro | I don't think he or she wants to put a grading on R. Actually, direct computation shows that the answer is no since there are no module maps from the quotient to the ring. | |
| Apr 30, 2015 at 18:13 | history | answered | John Palmieri | CC BY-SA 3.0 |