20 citations · 75 across the 17 of their papers we have counts for
24 papers
Moduli descriptions of v-sheaf local models
João Lourenço, Timo Richarz, Eva Viehmann +1
We propose a uniform moduli-theoretic description of the v-sheaf local model for an arbitrary parahoric group scheme and an arbitrary domin…
Categorical Künneth formulas for cohomological motives
Timo Richarz, Jakob Scholbach
The manuscript at hand systematically studies Künneth formulas at a categorical level. We give criteria for an abstract six functor formalism to satisfy the categorical Künneth for…
Frobenius rigidity in -homotopy theory
Timo Richarz, Jakob Scholbach
We study the homotopy fixed points under the Frobenius endomorphism on the stable -homotopy category of schemes in characteristic and prove a rigidity result for…
A modular ramified geometric Satake equivalence
Pramod N. Achar, João Lourenço, Timo Richarz +1
We extend the ramified geometric Satake equivalence due to Zhu (for tamely ramified groups) and the third named author (in full generality) from rational coefficients to include mo…
Normality of Schubert varieties in affine Grassmannians
Patrick Bieker, Timo Richarz
We classify all normal Schubert varieties in the affine Grassmannian of a semisimple group over an arbitrary field with special attention to small positive characteristic. The proo…
Constructible sheaves on schemes
Tamir Hemo, Timo Richarz, Jakob Scholbach
We present a uniform theory of constructible sheaves on arbitrary schemes with coefficients in topological or even condensed rings. This is accomplished by defining lisse sheaves t…
Fixed points under pinning-preserving automorphisms of reductive group schemes
Pramod N. Achar, João Lourenço, Timo Richarz +1
In this paper we determine the scheme-theoretic fixed points of pinned reductive group schemes acted upon by a group of pinning-preserving automorphisms. The results are used in a…
Singularities of local models
Najmuddin Fakhruddin, Thomas Haines, João Lourenço +1
We construct local models of Shimura varieties and investigate their singularities, with special emphasis on wildly ramified cases. More precisely, with the exception of odd unitar…
On the -adic theory of local models
Johannes Anschütz, Ian Gleason, João Lourenço +1
We prove the Scholze--Weinstein conjecture on the existence and uniqueness of local models for local Shimura varieties, as well as the test function conjecture of Haines--Kottwitz…
A categorical Künneth formula for constructible Weil sheaves
Tamir Hemo, Timo Richarz, Jakob Scholbach
We prove a Künneth-type equivalence of derived categories of lisse and constructible Weil sheaves on schemes in characteristic for various coefficients, including finite di…
Tate motives on Witt vector affine flag varieties
Timo Richarz, Jakob Scholbach
Relying on recent advances in the theory of motives we develope a general formalism for derived categories of motives with Q-coefficients on perfect (ind-)schemes. As an applicatio…
Néron blowups and low-degree cohomological applications
Arnaud Mayeux, Timo Richarz, Matthieu Romagny
We define dilatations of general schemes and study their basic properties. Dilatations of group schemes are -- in favorable cases -- again group schemes, called Néron blowups. We g…
The motivic Satake equivalence
Timo Richarz, Jakob Scholbach
We refine the geometric Satake equivalence due to Ginzburg, Beilinson-Drinfeld, and Mirković-Vilonen to an equivalence between mixed Tate motives on the double quotient $L^+ G \bac…
Normality and Cohen-Macaulayness of parahoric local models
Thomas J. Haines, Timo Richarz
We study the singularities of integral models of Shimura varieties and moduli stacks of shtukas with parahoric level structure. More generally our results apply to the Pappas-Zhu a…
The intersection motive of the moduli stack of shtukas
Timo Richarz, Jakob Scholbach
For a split reductive group G over a finite field, we show that the intersection (cohomology) motive of the moduli stack of iterated G-shtukas with bounded modification and level s…
Smoothness of Schubert varieties in twisted affine Grassmannians
Thomas J. Haines, Timo Richarz
We give a complete list of smooth and rationally smooth normalized Schubert varieties in the twisted affine Grassmannian associated with a tamely ramified group and a special verte…
On the normality of Schubert varieties: remaining cases in positive characteristic
Thomas J. Haines, João Lourenço, Timo Richarz
We study the geometry of equicharacteristic partial affine flag varieties associated to tamely ramified groups in characteristics dividing the order of the fundamental gr…
The Test Function Conjecture for Local Models of Weil-restricted groups
Thomas J. Haines, Timo Richarz
We prove the test function conjecture of Kottwitz and the first named author for local models of Shimura varieties with parahoric level structure attached to Weil-restricted groups…
The test function conjecture for parahoric local models
Thomas J. Haines, Timo Richarz
We prove the test function conjecture of Kottwitz and the first named author for local models of Shimura varieties with parahoric level structure, and their analogues in equal char…
Spaces with -action, hyperbolic localization and nearby cycles
Timo Richarz
We study families of algebraic spaces with a fiberwise -action and prove Braden's theorem on hyperbolic localization for arbitrary base schemes. As an application, we…
Affine Grassmannians and Geometric Satake Equivalences
Timo Richarz
I extend the ramified geometric Satake equivalence of Zhu from tamely ramified groups to include the case of general connected reductive groups. As a prerequisite I prove basic res…
On the Iwahori-Weyl group
Timo Richarz
Let be a discretely valued complete field with valuation ring and perfect residue field of cohomological dimension . In this paper, we generalize th…
A new approach to the geometric Satake equivalence
Timo Richarz
I give another proof of the geometric Satake equivalence from Mirkovic-Vilonen over a separably closed field. Using Galois descent, I obtain a canonical construction of the Galois…
Schubert varieties in twisted affine flag varieties and local models
Timo Richarz
Our concern in this paper is the dimension and inclusion relations of Schubert varieties in twisted partial affine flag varieties. In the end we apply our results to some local mod…