Timeline for Effectivity and Lower Shriek for Voevodsky Motives
Current License: CC BY-SA 3.0
8 events
| when toggle format | what | by | license | comment | |
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| Sep 15, 2017 at 7:56 | comment | added | Mikhail Bondarko | Note also that you cannot express the (Borel-Moore) motif of $U$ in terms of that of $X$ "after you get into motives over $\operatorname{Spec} k$". | |
| Sep 9, 2017 at 14:40 | comment | added | Mikhail Bondarko | I suspect that $\pi^X_!1_X(n)$ is effective if and only if $i\ge \dim(X)$. The "if" direction here is easy, and you can probably prove the "only if" implication by looking at some cohomology. If this is true then the answer to you question is certainly positive. | |
| Sep 9, 2017 at 11:10 | comment | added | Will Sawin | So if you twist by (1), isn't the second one ineffective? | |
| Sep 8, 2017 at 21:35 | comment | added | user114292 | Don't we have $\pi^{\mathbb{A}^1}_!\mathbf{1}_{\mathbb{A}^1}\simeq \mathbf{1}_k(-1)[-2]$ and $\pi^{\mathbb{G}_m}_!\mathbf{1}_{\mathbb{G}_m}\simeq \mathbf{1}_k[-1]\oplus\mathbf{1}_k(-1)[-2]$? | |
| Sep 8, 2017 at 21:09 | comment | added | Will Sawin | What about $X = \mathbb A^1, U = \mathbb G_m, n=1$? | |
| Sep 8, 2017 at 20:49 | history | edited | user114292 | CC BY-SA 3.0 |
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| Sep 8, 2017 at 20:07 | review | First posts | |||
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| Sep 8, 2017 at 20:02 | history | asked | user114292 | CC BY-SA 3.0 |