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Questions tagged [shimura-varieties]

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Central isogeny, Shimura varieties and exceptional cases

For a simple complex Lie algebra $\mathfrak g$, its weight lattice is not equal to the root lattice (i.e. the center of its simply connected form is a non-trivial finite group) iff $\mathfrak g$ is of ...
Zhiyu's user avatar
  • 6,622
4 votes
0 answers
241 views

What do we do when $G$ doesn't have a Shimura variety?

Let $G$ be a reductive group. If one can associate to $G$ a Shimura datum $(G,X)$, then the étale cohomology of the associated Shimura variety $\operatorname{Sh}(G,X)$ is a strong tool for the ...
Loading's user avatar
  • 57
1 vote
0 answers
182 views

"Reflex field" for $\mathbb H/\Gamma$ for $\Gamma$ non-congruence

Suppose $\Gamma$ is a non-congruence arithmetic subgroup of $PGL_2(\mathbb Z)$, and $\mathbb H$ is the upper half plane of $\mathbb C$. Then by Belyi's theorem we know $\mathbb H/\Gamma$ is an ...
Richard's user avatar
  • 785
1 vote
0 answers
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Galois group of shimura varieties with different level structure

Let $(G,X)$ be a shimura data, and $K$ an open compact neat subgroup of $G(\mathbb A_f)$. Suppose $K'\subset K$ is open and normal, then, I see in many references that the finite etale cover $Sh(G,X)_{...
Richard's user avatar
  • 785
0 votes
0 answers
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Descend local system to the canonical model of Shimura varieties

Suppose $(G,X)$ is a Shimura data, and $E$ be its reflex field. In page 33 of this paper, it constructs an etale local system on the canonical model $\mathrm{Sh}(G,X)_{K,E}$ (variety over $E$) for any ...
Richard's user avatar
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