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Related papers: Local models in the ramified case I. The EL-case

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We study integral models, so-called Pappas-Rapoport or splitting models, of some PEL Shimura Varieties whose data are ramified at a prime p. We show that except in a specific case, these models are smooth when there is no level at p, and we…

Algebraic Geometry · Mathematics 2020-11-02 Stéphane Bijakowski , Valentin Hernandez

Let $F$ be a complete discretely valued field with ring of integers $\mathcal{O}$ and residue field of characteristic $p>2$. Let $G=\operatorname{GO}_{2n}$ denote the split orthogonal similitude group over $F$. For any parahoric level…

Number Theory · Mathematics 2026-05-15 Jie Yang

We study some integral model of P.E.L. Shimura varieties of type A for ramified primes. Precisely, we look at the Pappas-Rapoport model (or splitting model) of some unitary Shimura varieties for which there is ramification in the degree 2…

Algebraic Geometry · Mathematics 2024-01-17 Stéphane Bijakowski , Valentin Hernandez

We prove a criterion for the normality of Schubert varieties in twisted affine Grassmannians in terms of the order of the algebraic fundamental group of a certain Levi subgroup, in particular in small positive characteristic. As an…

Algebraic Geometry · Mathematics 2025-10-07 Patrick Bieker

This article provides a ``local'' complementary to the previous results concerning the local models for the moduli stacks of ``global'' $G$-shtukas. Here we study the geometry of Rapoport-Zink spaces for local $P$-shtukas by constructing…

Number Theory · Mathematics 2023-12-07 Esmail Arasteh Rad

We construct integral models and special affinoids of suitable tubular neighborhoods of local Shimura varieties at depth-zero. We show that the reductions of the special affinoids over suitable tamely ramified extensions are realized as…

Number Theory · Mathematics 2025-08-14 Yuta Takaya

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

The motivation for this paper is the study of arithmetic properties of Shimura varieties, in particular the Newton stratification of the special fiber of a suitable integral model at a prime with parahoric level structure. This is closely…

Algebraic Geometry · Mathematics 2019-05-13 Ulrich Goertz , Xuhua He , Sian Nie

We construct local models for wildly ramified unitary similitude groups of odd dimension $n\geq 3$ with special parahoric level structure and signature $(n-1,1)$. We first give a lattice-theoretic description for parahoric subgroups using…

Number Theory · Mathematics 2025-08-15 Jie Yang

The supersingular locus in the fiber at p of a Shimura variety attached to a unitary similitude group GU(1,n-1) over Q is uniformized by a formal scheme \Cal N. In the case when p is inert, we define special cycles Z(x) in \Cal N,…

Algebraic Geometry · Mathematics 2011-02-18 Stephen Kudla , Michael Rapoport

We prove the Kudla--Rapoport conjecture for Kr\"amer models of unitary Rapoport--Zink spaces at ramified places. It is a precise identity between arithmetic intersection numbers of special cycles on Kr\"amer models and modified derived…

Number Theory · Mathematics 2023-07-04 Qiao He , Chao Li , Yousheng Shi , Tonghai Yang

We prove the geometrical Satake isomorphism for a reductive group defined over F=k((t)), and split over a tamely ramified extension. As an application, we give a description of the nearby cycles on certain Shimura varieties via the…

Representation Theory · Mathematics 2013-01-01 Xinwen Zhu

The special fiber of the local model of a PEL Shimura variety with Iwahori-type level structure admits a cellular decomposition. The set of strata is in a natural way a finite subset of the affine Weyl group determined by the Shimura data.…

Representation Theory · Mathematics 2007-05-23 T. Haines , B. C. Ngo

We study local models that describe the singularities of Shimura varieties of non-PEL type for orthogonal groups at primes where the level subgroup is given by the stabilizer of a single lattice. In particular, we use the Pappas-Zhu…

Algebraic Geometry · Mathematics 2022-04-27 Ioannis Zachos

We determine the type of the zeta functions and the range of the dimensions of the moduli spaces of finite flat models of two-dimensional local Galois representations over finite fields. This gives a generalization of Raynaud's theorem on…

Number Theory · Mathematics 2020-11-24 Naoki Imai

Lyubeznik's conjecture, (\cite{Ly1}, Remark 3.7) asserts the finiteness of the set ssociated primes of local cohomology modules for regular rings. But, in the case of ramified regular local ring, it is open. Recently, in Theorem 1.2 of…

Commutative Algebra · Mathematics 2015-12-18 Rajsekhar Bhattacharyya

Local models of Shimura varieties in type A can be realized inside products of Grassmannians via certain linear algebraic conditions. Laumon suggested a generalization which can be identified with a family over a line whose general fibers…

Algebraic Geometry · Mathematics 2023-07-06 Evgeny Feigin , Martina Lanini , Alexander Pütz

In this paper, we show examples of local cohomology modules over ramified regular local ring, having finite set of associated primes. In doing so we consider our ramified regular local ring as Eisenstein extension of an unramified regular…

Commutative Algebra · Mathematics 2024-04-09 Rajsekhar Bhattacharyya

We classify group schemes in terms of their Cartier modules. We also prove the equivalence of different definitions of the tangent space and the dimension for these group schemes; in particular, the minimal dimension of a formal group law…

Algebraic Geometry · Mathematics 2007-05-23 M. V. Bondarko

We extend the group theoretic construction of local models of Pappas and Zhu 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…

Number Theory · Mathematics 2019-02-20 Brandon Levin