scholarly journals Motivic Serre invariants and Weil restriction

2008 ◽  
Vol 319 (4) ◽  
pp. 1585-1610 ◽  
Author(s):  
Johannes Nicaise ◽  
Julien Sebag
Keyword(s):  
Weil Restriction

Automorphisms, isomorphisms, and Tits classification

2015 ◽  
Author(s):  
Brian Conrad ◽  
Gopal Prasad
Keyword(s):  
Affine Group ◽  
Classification Theorem ◽  
Isomorphism Theorem ◽  
Reductive Groups ◽  
Semisimple Groups ◽  
Dynkin Diagrams ◽  
Weil Restriction ◽  
Characteristic 2 ◽  
Smooth Affine

This chapter considers automorphisms, isomorphisms, and Tits classification. It begins by establishing a version of the Isomorphism Theorem for pseudo-split pseudo-reductive groups, along with a pseudo-reductive variant of the Isogeny Theorem for split connected semisimple groups. The key to both proofs is a technique to construct pseudo-reductive subgroups of an ambient smooth affine group. Some instructive examples over imperfect fields k of characteristic 2 are given. The chapter goes on to discuss the behavior of the k-group ZG,C with respect to Weil restriction in the pseudoreductive case. It also describes automorphism schemes for pseudo-reductive groups, focusing only on the pseudo-semisimple case because commutative pseudo-reductive groups that are not tori generally have a non-representable automorphism functor. Finally, it examines Tits-style classification, using Dynkin diagrams to express the classification theorem.

scholarly journals Local models for Weil-restricted groups

2016 ◽  
Vol 152 (12) ◽  
pp. 2563-2601 ◽  
Author(s):  
Brandon Levin
Keyword(s):  
Hecke Algebra ◽  
Shimura Varieties ◽  
Reductive Groups ◽  
Local Models ◽  
Central Function ◽  
Nearby Cycles ◽  
Weil Restriction ◽  
Trace Of Frobenius ◽  
Invent Math

We extend the group-theoretic construction of local models of Pappas and Zhu [Local models of Shimura varieties and a conjecture of Kottwitz, Invent. Math.194(2013), 147–254] to the case of groups obtained by Weil restriction along a possibly wildly ramified extension. This completes the construction of local models for all reductive groups when$p\geqslant 5$. We show that the local models are normal with special fiber reduced and study the monodromy action on the sheaves of nearby cycles. As a consequence, we prove a conjecture of Kottwitz that the semi-simple trace of Frobenius gives a central function in the parahoric Hecke algebra. We also introduce a notion of splitting model and use this to study the inertial action in the case of an unramified group.

scholarly journals Constructing pairing-friendly hyperelliptic curves using Weil restriction

2011 ◽  
Vol 131 (5) ◽  
pp. 959-983 ◽  
Author(s):  
David Mandell Freeman ◽  
Takakazu Satoh
Keyword(s):  
Hyperelliptic Curves ◽  
Weil Restriction

scholarly journals Finite Weil restriction of curves

2014 ◽  
Vol 176 (2) ◽  
pp. 197-218
Author(s):  
E. V. Flynn ◽  
D. Testa
Keyword(s):  
Weil Restriction

Formal Néron models and Weil restriction

2000 ◽  
Vol 316 (3) ◽  
pp. 437-463 ◽  
Author(s):  
Alessandra Bertapelle
Keyword(s):  
Weil Restriction ◽  
Neron Models ◽  
Néron Models

scholarly journals The elementary obstruction and the Weil restriction

2008 ◽  
Vol 128 (2) ◽  
pp. 137-146
Author(s):  
Tim Wouters
Keyword(s):  
Weil Restriction

scholarly journals Smooth affine group schemes over the dual numbers

2019 ◽  
Vol Volume 3 ◽  
Author(s):  
Matthieu ROMAGNY ◽  
Dajano Tossici
Keyword(s):  
Commutative Ring ◽  
Group Algebra ◽  
Group Scheme ◽  
Affine Group ◽  
Unipotent Group ◽  
Dual Numbers ◽  
Group Schemes ◽  
Weil Restriction ◽  
International Audience ◽  
Smooth Affine

International audience We provide an equivalence between the category of affine, smooth group schemes over the ring of generalized dual numbers $k[I]$, and the category of extensions of the form $1 \to \text{Lie}(G, I) \to E \to G \to 1$ where G is an affine, smooth group scheme over k. Here k is an arbitrary commutative ring and $k[I] = k \oplus I$ with $I^2 = 0$. The equivalence is given by Weil restriction, and we provide a quasi-inverse which we call Weil extension. It is compatible with the exact structures and the $\mathbb{O}_k$-module stack structures on both categories. Our constructions rely on the use of the group algebra scheme of an affine group scheme; we introduce this object and establish its main properties. As an application, we establish a Dieudonné classification for smooth, commutative, unipotent group schemes over $k[I]$. Nous construisons une équivalence entre la catégorie des schémas en groupes affines et lisses sur l'anneau des nombres duaux généralisés k[I], et la catégorie des extensions de la forme 1 → Lie(G, I) → E → G → 1 où G est un schéma en groupes affine, lisse sur k. Ici k est un anneau commutatif arbitraire et k[I] = k ⊕ I avec I 2 = 0. L'équivalence est donnée par la restriction de Weil, et nous construisons un foncteur quasi-inverse explicite que nous appelons extension de Weil. Ces foncteurs sont compatibles avec les structures exactes et avec les structures de champs en O k-modules des deux catégories. Nos constructions s'appuient sur le schéma en algèbres de groupe d'un schéma en groupes affines, que nous introduisons et dont nous donnons les propriétés principales. En application, nous donnons une classification de Dieudonné pour les schémas en groupes commutatifs, lisses, unipotents sur k[I] lorsque k est un corps parfait.

scholarly journals Weil restriction and the Quot scheme

2015 ◽  
Vol 2 (4) ◽  
pp. 514-534
Author(s):  
Roy Skjelnes
Keyword(s):  
Quot Scheme ◽  
Weil Restriction
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