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Let G be a connected unipotent group over a finite field F_q with q elements. In this article we propose a definition of L-packets of complex irreducible representations of the finite group G(F_q) and give an explicit description of…

Representation Theory · Mathematics 2010-11-24 Mitya Boyarchenko

We begin the study of character sheaves on a not necessarily connected reductive group, extending the known theory for connected groups.

Representation Theory · Mathematics 2007-05-23 G. Lusztig

A finite group $G$ is said to be admissible over a field $F$ if there exists a division algebra $D$ central over $F$ with a maximal subfield $L$ such that $L/F$ is Galois with group $G$. In this paper we give a complete characterization of…

Rings and Algebras · Mathematics 2023-08-25 Yael Davidov

We compute the Frobenius trace functions of mirabolic character sheaves defined over a finite field. The answer is given in terms of the character values of general linear groups over the finite field, and the structure constants of…

Algebraic Geometry · Mathematics 2026-04-21 Michael Finkelberg , Victor Ginzburg , Roman Travkin

Let $G$ be a connected reductive group over $F_q$, where $q$ is large enough and the center of $G$ is connected. We are concerned with Lusztig's theory of {\em character sheaves}, a geometric version of the classical character theory of the…

Representation Theory · Mathematics 2008-01-21 Meinolf Geck , David Hézard

This article is concerned with the relative McKay conjecture for finite reductive groups. Let G be a connected reductive group defined over the finite field F_q of characteristic p>0 with corresponding Frobenius map F. We prove that if the…

Representation Theory · Mathematics 2014-02-26 Olivier Brunat

In this article, we study the elements with disconnected centralizer in the Brauer complex associated to a simple algebraic group G defined over a finite field with corresponding Frobenius map F and derive the number of F-stable semisimple…

Representation Theory · Mathematics 2010-03-18 Olivier Brunat

Let G denote a connected, quasi-split reductive group over a field F that is complete with respect to a discrete valuation and that has a perfect residue field. Under mild hypotheses, we produce a subset of the Lie algebra g(F) that picks…

Representation Theory · Mathematics 2019-03-13 Jeffrey D. Adler , Jessica Fintzen , Sandeep Varma

Let H be a connected reductive group over an algebraically closed field. We define a surjective map from the set CS(H) of unipotent character sheaves on H (up to isomorphism) to the set of strata of H. To do this we use the generalized…

Representation Theory · Mathematics 2023-11-02 G. Lusztig

Let G be a finite group. We explore the model theoretic properties of the class of differential fields of characteristic zero in m commuting derivations equipped with a G-action by differential field automorphisms. In the language of…

Logic · Mathematics 2021-01-19 Daniel Max Hoffmann , Omar León Sánchez

The Graded Classification Conjecture (GCC) states that the pointed $K_0^{\operatorname{gr}}$-group is a complete invariant of the Leavitt path algebras of finite graphs when these algebras are considered with their natural grading by…

Rings and Algebras · Mathematics 2026-03-03 Lia Vas

We show that a connected split reductive group G over a field of characteristic 0 is uniquely determined up to isomorphism by specifying a maximal torus T of G, the set of isomorphism classes of irreducible representations of G, and the…

Representation Theory · Mathematics 2007-05-23 CheeWhye Chin

In this paper, we prove Lusztig's conjecture for finite special linear groups, i.e., we show that characteristic functions of character sheaves coincide with almost characters up to scalar constants, under the condition that the…

Representation Theory · Mathematics 2007-05-23 Toshiaki Shoji

Fix a scheme $X$ over a field of characteristic zero that is equipped with an action of a reductive algebraic group $G$. We give necessary and sufficient conditions for a $G$-equivariant coherent sheaf on $X$ or a bounded-above complex of…

Algebraic Geometry · Mathematics 2008-04-21 Thomas Nevins

We consider interpretable topological spaces and topological groups in a $p$-adically closed field $K$. We identify a special class of "admissible topologies" with topological tameness properties like generic continuity, similar to the…

Logic · Mathematics 2022-08-23 Will Johnson

We give a combinatorial description of the dg category of character sheaves on a complex reductive group $G$, extending results of [Li] for $G$ simply-connected. We also explicitly identify the parabolic induction/restriction functors.

Representation Theory · Mathematics 2023-05-09 Penghui Li

Recently, a strong exponential character bound has been established in [3] for all elements $g \in \mathbf{G}^F$ of a finite reductive group $\mathbf{G}^F$ which satisfy the condition that the centraliser $C_{\mathbf{G}}(g)$ is contained in…

Representation Theory · Mathematics 2022-02-07 Jay Taylor , Pham H. Tiep

Let $G$ be a connected reductive algebraic group defined over the finite field $\F_q$, where $q$ is a power of a good prime for $G$, and let $F$ denote the corresponding Frobenius endomorphism, so that $G^F$ is a finite reductive group. Let…

Representation Theory · Mathematics 2011-08-09 Matthew C. Clarke

In this paper we prove a new characterization of the distinguished unipotent orbits of a connected reductive group over an algebraically closed field of characteristic 0. For classical groups we prove the characterization by a combinatorial…

Representation Theory · Mathematics 2024-09-11 Alexander Bertoloni Meli , Teruhisa Koshikawa , Jonathan Leake

In this paper, we prove that if the Frobenius traces agree at all but finitely many places, then two $l$-adic Galois representations, associated to rank-$2$ non-CM Drinfeld modules of generic characteristic, are isomorphic. As a…

Number Theory · Mathematics 2026-05-05 Chien-Hua Chen