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Related papers: EKOR strata for Shimura varieties with parahoric l…

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We study $p$-adic integral models of certain PEL Shimura varieties with level subgroup at $p$ related to the $\Gamma_1(p)$-level subgroup in the case of modular curves. We will consider two cases: the case of Shimura varieties associated…

Algebraic Geometry · Mathematics 2015-06-18 Richard Shadrach

We prove a conjecture of Pappas and Rapoport for all Shimura varieties of abelian type with parahoric level structure when $p>3$ by showing that the Kisin-Pappas-Zhou integral models of Shimura varieties of abelian type are canonical. In…

Number Theory · Mathematics 2024-02-09 Patrick Daniels , Alex Youcis

In this paper, we study the behavior of Ekedahl-Oort strata under natural embeddings between the good reductions modulo $p$ of GSpin Shimura varieties and Rapoport-Smithling-Zhang unitary Shimura varieties, a prototypical setting for the…

Number Theory · Mathematics 2026-05-27 Yan Qijun , Zhang Chao

We establish basic results on p-adic shtukas and apply them to the theory of local and global Shimura varieties, and on their interrelation. We construct canonical integral models for (local, and global) Shimura varieties of Hodge type with…

Number Theory · Mathematics 2023-10-27 Georgios Pappas , Michael Rapoport

We investigate the bad reduction of certain Shimura varieties (associated to the symplectic group). More precisely, we look at a model of the Shimura variety at a prime p, with parahoric level structure at p. We show that this model is…

Algebraic Geometry · Mathematics 2007-05-23 Ulrich Goertz

We construct universal $G$-zips on good reductions of the Pappas-Rapoport splitting models for PEL-type Shimura varieties. We study the induced Ekedahl-Oort stratification, which sheds new light on the mod $p$ geometry of splitting models.…

Algebraic Geometry · Mathematics 2025-08-14 Xu Shen , Yuqiang Zheng

For a prime $p>2$, Kisin and Pappas constructed parahoric integral models at $p$ for Shimura varieties attached to Shimura data $(G,X)$ of abelian type such that $G$ splits over a tamely ramified extension of $\mathbb{Q}_p$. A certain…

Algebraic Geometry · Mathematics 2019-03-19 Chao Zhang

This paper is a contribution to the general problem of giving an explicit description of the basic locus in the reduction modulo $p$ of Shimura varieties. Motivated by \cite{Vollaard-Wedhorn} and \cite{Rapoport-Terstiege-Wilson}, we…

Algebraic Geometry · Mathematics 2013-11-26 Ulrich Goertz , Xuhua He

We develop tools to study spaces of $p$-divisible groups and Abelian varieties with additional structure. More precisely, we extend the definition of parahoric (Dieudonn\'e) $(\mathcal{G}, \mu)$-displays given by Pappas to not necessarily…

Algebraic Geometry · Mathematics 2023-11-02 Manuel Hoff

For a Shimura variety of Hodge type with hyperspecial level structure at a prime $p$, Vasiu and Kisin constructed a smooth integral model (namely the integral canonical model) uniquely determined by a certain extension property. We define…

Algebraic Geometry · Mathematics 2017-07-05 Chao Zhang

We consider the local model of a Shimura variety of PEL type, with the unitary similitudes corresponding to a ramified quadratic extension of $\mathbb{Q}_p$ as defining group. We examine the cases where the level structure at $p$ is given…

Algebraic Geometry · Mathematics 2010-05-19 Kai Arzdorf

This paper concerns the characteristic-$p$ fibers of $\mathsf{GU}(q-2,2)$ Shimura varieties, which classify abelian varieties with additional structure. These Shimura varieties admit two stratifications of interest: the Ekedahl-Oort…

Number Theory · Mathematics 2025-10-03 Emerald Andrews , Deewang Bhamidipati , Maria Fox , Heidi Goodson , Steven R. Groen , Sandra Nair

Let $S$ be the special fibre of a Shimura variety of Hodge type, with good reduction at a place above $p$. We give an alternative construction of the zip period map for $S$, which is used to define the Ekedahl-Oort strata of $S$. The method…

Algebraic Geometry · Mathematics 2021-09-03 Qijun Yan

In the paper four stratifications in the reduction modulo $p$ of a general Shimura variety are studied: the Newton stratification, the Kottwitz-Rapoport stratification, the Ekedahl-Oort stratification and the Ekedahl-Kottwitz-Oort-Rapoport…

Algebraic Geometry · Mathematics 2015-09-28 Xuhua He , Michael Rapoport

In this paper, we study the $\mu$-ordinary locus of a Shimura variety with parahoric level structure. Under the axioms in \cite{HR}, we show that $\mu$-ordinary locus is a union of some maximal Ekedahl-Kottwitz-Oort-Rapoport strata…

Algebraic Geometry · Mathematics 2017-06-13 Xuhua He , Sian Nie

Let $F$ be a totally real field, $p$ a prime that we allow to ramify in $F$, and $B$ a quaternion algebra over $F$ which is split at places over $p$. We consider a smooth $p$-adic integral model, the Pappas-Rapoport model, of the…

Number Theory · Mathematics 2025-05-20 Gabriel Micolet

We continue our study of the reduction of PEL Shimura varieties with parahoric level structure at primes p at which the group that defines the Shimura variety ramifies. We describe "good" $p$-adic integral models of these Shimura varieties…

Algebraic Geometry · Mathematics 2007-05-23 G. Pappas , M. Rapoport

This paper concerns the characteristic-$p$ fibers of $\mathsf{GU}(3,2)$ Shimura varieties. Such Shimura varieties parametrize abelian varieties in characteristic $p$ of dimension $5$ with an action of signature $(3,2)$ by an order in an…

Number Theory · Mathematics 2025-10-02 Emerald Andrews , Deewang Bhamidipati , Maria Fox , Heidi Goodson , Steven R. Groen , Sandra Nair

Consider a PEL-Shimura variety associated to a unitary group that splits over an unramified extension of Q_p. Rapoport and Zink have defined a model of the Shimura variety over the ring of integers of the completion of the reflex field at a…

Algebraic Geometry · Mathematics 2009-09-25 U. Goertz

Under the axiom of He and Rapoport for the stratifications of Shimura varieties, we explain a result of G\"{o}rtz, He and Nie that the EKOR strata contained in the basic loci can be described as a disjoint union of Deligne-Lusztig…

Number Theory · Mathematics 2020-01-01 Haining Wang