Timeline for Open affine subscheme of affine scheme which is not principal
Current License: CC BY-SA 3.0
12 events
| when toggle format | what | by | license | comment | |
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| S Feb 3, 2016 at 18:41 | history | suggested | Snow | CC BY-SA 3.0 |
Editted very confusing notation. Now X and U only mean one thing.
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| Feb 3, 2016 at 18:24 | review | Suggested edits | |||
| S Feb 3, 2016 at 18:41 | |||||
| Nov 16, 2015 at 8:18 | comment | added | Matthieu Romagny | I agree it is not clear why $D(X,Y)$ is not principal. Also the role of $U$ and $V$ is not clear: can you take $U=V=1$ ? | |
| May 15, 2015 at 19:36 | comment | added | Isac Hedén | @Alison Miller: Take f_1=X, f_2=Y with notation from Hartshorne exercise II.2.17. What we need, is that U_X and U_Y are affine, and this obviously holds since U_X is the principal open subset D(X) of Spec(A), and similarly for U_Y. | |
| Dec 29, 2014 at 6:12 | comment | added | Jonathan Wise | How do you show $D(X,Y)$ is not principal? | |
| Oct 4, 2014 at 1:53 | comment | added | Alison Miller | Why are the open sets X_f and X_g affine? | |
| Jan 31, 2013 at 9:09 | comment | added | solbap | @benblumsmith see Hartshorne excercise II.2.17 | |
| Nov 27, 2012 at 1:19 | comment | added | benblumsmith | Why does $Yf+Xg=1$ imply that $U$ is affine? | |
| Jan 16, 2012 at 19:32 | comment | added | Thomas Kahle | You have used $U$ twice... but well. | |
| Dec 29, 2009 at 1:23 | comment | added | Martin Brandenburg | finally an easy example :-) | |
| Dec 20, 2009 at 8:07 | history | edited | Hailong Dao | CC BY-SA 2.5 |
deleted 1 characters in body
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| Nov 30, 2009 at 1:57 | history | answered | Hailong Dao | CC BY-SA 2.5 |