ABOUT GALOIS REDUCIBILITY OF TORSION COHOMOLOGY CLASSES FOR KHT SHIMURA VARIETIES - Archive ouverte HAL
Pré-Publication, Document De Travail Année : 2019

ABOUT GALOIS REDUCIBILITY OF TORSION COHOMOLOGY CLASSES FOR KHT SHIMURA VARIETIES

Résumé

We pursue the original strategy of my paper at JIMJ and we give a new criterion so that the localization of the cohomology of KHT Shimura variety is free. Precisely let $G$ be a similitude group with signatures $(1,d-1),(0,d),\cdots,(0,d)$, and $V_{\xi,\mathbb Z_l}$ a local system associated to a fixed algebraic representation $\xi$ of $G(\mathbb Q)$. Consider a system $\mathfrrak m$ of Hecke eigenvalues appearing in the free quotient of the cohomology group in middle degree of the Shimura variety $Sh_K$ associated to $G$ and with coefficients in $V_{\xi,\mathbb Z_l}$. Then if the modulo $l$ galoisian representation $\bar \rho_{\mathfrak m}$ is irreducible of dimension $d$, and essentially if $l \geq d+1$, the localization at $\mathfrak m$ of every cohomology group of $Sh_K$ with coefficients in $V_{\xi,\mathbb Z_l}$, is free.
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Dates et versions

hal-02080476 , version 1 (26-03-2019)
hal-02080476 , version 2 (14-09-2019)
hal-02080476 , version 3 (26-10-2019)
hal-02080476 , version 4 (27-04-2020)

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  • HAL Id : hal-02080476 , version 1

Citer

Pascal Boyer. ABOUT GALOIS REDUCIBILITY OF TORSION COHOMOLOGY CLASSES FOR KHT SHIMURA VARIETIES. 2019. ⟨hal-02080476v1⟩
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