Grassmanniennes affines tordues sur les entiers
We generalize the works of Pappas–Rapoport–Zhu on twisted affine Grassmannians to the wildly ramified case under mild assumptions. This rests on a construction of certain smooth affine $\mathbb {Z}[t]$ -groups with connected fibers of parahoric type, motivated by previous work of Tits. The res...
| Main Author: | |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Cambridge University Press
2023-01-01
|
| Series: | Forum of Mathematics, Sigma |
| Subjects: | |
| Online Access: | https://www.cambridge.org/core/product/identifier/S205050942300004X/type/journal_article |
| Summary: | We generalize the works of Pappas–Rapoport–Zhu on twisted affine Grassmannians to the wildly ramified case under mild assumptions. This rests on a construction of certain smooth affine
$\mathbb {Z}[t]$
-groups with connected fibers of parahoric type, motivated by previous work of Tits. The resulting
$\mathbb {F}_p(t)$
-groups are pseudo-reductive and sometimes non-standard in the sense of Conrad–Gabber–Prasad, and their
$\mathbb {F}_p [\hspace {-0,5mm}[ {t} ]\hspace {-0,5mm}] $
-models are parahoric in a generalized sense. We study their affine Grassmannians, proving normality of Schubert varieties and Zhu’s coherence theorem. |
|---|---|
| ISSN: | 2050-5094 |