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How far can the elementary description of centralizers of parabolic subalgebras of Hecke algebras of finite real reflection groups be generalized to the complex reflection group case? In this paper we begin to answer this question by…

Representation Theory · Mathematics 2007-07-20 Andrew Francis

Given a group, we construct a fundamental additive functor on its orbit category. We prove that any isomorphism conjecture valid for this fundamental isomorphism functor holds for all additive functors, like K-theory, cyclic homology,…

K-Theory and Homology · Mathematics 2012-02-29 Paul Balmer , Goncalo Tabuada

In the present article we define an integral analogue of Chow-K\"unneth decomposition for \'etale motives. By using families of conservative functors we are able to establish a decomposition of the \'etale motive of commutative group…

Algebraic Geometry · Mathematics 2024-03-04 Ivan Rosas-Soto

We make explicit Serre's generalization of the Sato-Tate conjecture for motives, by expressing the construction in terms of fiber functors from the motivic category of absolute Hodge cycles into a suitable category of Hodge structures of…

Number Theory · Mathematics 2016-02-26 Grzegorz Banaszak , Kiran S. Kedlaya

Ever since the introduction of motivic homotopy theory, as a well-proposed approximation of Grothendieck's dream, algebraic geometers then have the chance to study schemes via a homotopy theory. However topologists also found that lifting…

Algebraic Geometry · Mathematics 2025-12-09 Xin Tong

This work is dedicated to the construction of a new motivic homotopy theory for (log) schemes, generalizing Morel-Voevodsky's (un)stable $\mathbb{A}^1$-homotopy category. Our framework can be used to represent log topological Hochschild and…

Algebraic Geometry · Mathematics 2025-07-03 Federico Binda , Doosung Park , Paul Arne Østvær

We propose a formulation of the Equivariant Tamagawa Number Conjecture for modular motives with coefficients in universal deformation rings and Hecke algebras; something which seems to have been heretofore missing because the complexes of…

Number Theory · Mathematics 2014-04-25 Olivier Fouquet

We construct the geometric Satake equivalence for quasi-split reductive groups over nonarchimedean local fields, using \'etale Artin-Tate motives with $\mathbb{Z}[\frac{1}{p}]$-coefficients. We consider local fields of both equal and mixed…

Representation Theory · Mathematics 2026-03-26 Thibaud van den Hove

Let $\mathbb{k}$ be a field of characteristic $p$. We introduce a formalism of mixed sheaves with coefficients in $\mathbb{k}$ and showcase its use in representation theory. More precisely, we construct for all quasi-projective schemes $X$…

Representation Theory · Mathematics 2019-04-16 Jens Niklas Eberhardt , Shane Kelly

Let G be an adjoint simple algebraic group of inner type. We express the Chow motive (with integral coefficients) of some anisotropic projective G-homogeneous varieties in terms of motives of simpler G-homogeneous varieties, namely, those…

Algebraic Geometry · Mathematics 2008-03-07 B. Calmes , V. Petrov , N. Semenov , K. Zainoulline

Let $G$ be a reductive group over $\mathbb{F}_{p}$ with associated finite group of Lie type $G^{F}$. Let $T$ be a maximal torus contained inside a Borel $B$ of $G$. We relate the (rational) Tate motives of $\text{B}G^{F}$ with the…

Algebraic Geometry · Mathematics 2024-07-29 Can Yaylali

We prove a motivic enhancement of the classical Picard--Lefschetz formula. Our proof is completely motivic, and yields a description of the motivic nearby cycles at a quasi-homogeneous singularity, as well as its monodromy, in terms of an…

Algebraic Geometry · Mathematics 2025-10-15 Ran Azouri , Emil Jacobsen

In this thesis we give two applications of Ayoub's motivic nearby cycles functor: First we give a generalization of Grothendieck's classical local monodromy theorem. In the classical setup we show that the inertia group acts…

Algebraic Geometry · Mathematics 2023-05-08 Benedikt Preis

In this paper we generalize and study a notion of (unipotent) nearby cycles over a higher dimensional base based on Be\u{i}linson's description of unipotent nearby cycles, following an idea of Gaitsgory. This generalization, in the setting…

Algebraic Geometry · Mathematics 2024-02-01 Pramod N. Achar , Simon Riche

We construct derived fundamental group schemes for Tate motives over connected smooth schemes over fields. We show that there exists a pro affine derived group scheme over the rationals such that its category of perfect representations…

Algebraic Geometry · Mathematics 2010-11-02 Markus Spitzweck

Using the framework relating hypergeometric motives to modular forms, we define an explicit family of weight 2 Hecke eigenforms with complex multiplication. We use the theory of ${}_2F_1(1)$ hypergeometric series and Ramanujan's theory of…

Number Theory · Mathematics 2025-02-14 Esme Rosen

We improve some foundational connectivity results and the relative Hurewicz theorem in motivic homotopy theory, study functorial central series in motivic local group theory, establish the existence of functorial Moore--Postnikov…

Algebraic Geometry · Mathematics 2025-12-03 Aravind Asok , Tom Bachmann , Michael J. Hopkins

We settle a long-standing problem in the theory of Hecke algebras of complex reflection groups by constructing many (graded) integral cellular bases of these algebras. As applications, we explicitly construct the simple modules of Ariki's…

Representation Theory · Mathematics 2026-02-18 C. Bowman

We establish a connection between certain unique models, or equivalently unique functionals, for representations of p-adic groups and linear characters of their corresponding Hecke algebras. This allows us to give a uniform evaluation of…

Representation Theory · Mathematics 2015-07-29 Ben Brubaker , Daniel Bump , Solomon Friedberg

We show in many cases the existence of adjoints to extension of scalars on categories of motivic nature, in the framework of field extensions. This is to be contrasted with the more classical situation where one deals with a finite type…

Algebraic Geometry · Mathematics 2020-06-04 Bruno Kahn