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Dec
23
comment Fiber functors to derived categories
Is it really true that $G$ linearly reductive implies $\delta=0$? For example, consider a cts homomorphism $\Gamma\rightarrow G(k)$ where $\Gamma$ is a procyclic group ($k$ could be discrete or have an interesting topology). Then the functor $V\mapsto V^\Gamma$ may not be exact, but the group cohomology $H^i(\Gamma,V)$ is likely computed by the complex $V\rightarrow V$, where the map is $\gamma-1$ for a topological generator $\gamma$ of $\Gamma$. If $V\mapsto V^\Gamma$ is exact, it looks to me like I get 2 $G$-torsors (one for $H^0$, one for $H^1$), but if not, I don't think $\delta=0$.
Dec
22
awarded  Nice Question
Oct
7
awarded  Yearling
Jun
25
awarded  Citizen Patrol
Jan
15
answered the dual abelian scheme
Oct
7
awarded  Yearling
Oct
4
awarded  Nice Question
Sep
30
accepted Are D_dR and D_st “potentially comparable”?
Sep
30
comment Are D_dR and D_st “potentially comparable”?
Great, thanks!
Sep
29
asked Are D_dR and D_st “potentially comparable”?
Jul
3
awarded  Enlightened
Jul
3
awarded  Nice Answer
Jul
2
comment Some help in digesting a paragraph in the introduction of Deligne/Rapoport's “Les Schemas de Modules de Courbes Elliptique”
Yes, we're thinking of $(\mathbf{Z}/n\mathbf{Z})^2$ as a group scheme. Over any base scheme $S$, the scheme structure on $(\mathbf{Z}/n\mathbf{Z})_S^2$ is just $n^2$ disjoint copies of $S$.
Jul
2
awarded  Enlightened
Jul
2
awarded  Nice Answer
Jul
2
answered Some help in digesting a paragraph in the introduction of Deligne/Rapoport's “Les Schemas de Modules de Courbes Elliptique”
May
9
awarded  Nice Answer
Jan
20
asked Fiber functors to derived categories
Dec
25
comment Deformation of ordinary p-divisible groups via Grothendieck-Messing
I think you're implicitly asserting that the map $\omega_{G^m}\rightarrow D(G_0)(W(k))$ coming from $G'$ is the same as the composition $\omega_{G^m}\rightarrow \omega_G\rightarrow D(G_0)(W(k))$.
Dec
24
comment Shape of snowflakes
It's not the same as assuming no molecules attach at the same time, because in your random model you're effectively adjusting the probability of attachment based on the size of the snowflake. If anything, you want to adjust the probabilities based on the geometry --- I would guess that available vertices deep "inside" the snowflake would have lower probabilities of attachment.