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In [AGRS] a multiplicity one theorem is proven for general linear groups, orthogonal groups and unitary groups ($GL, O,$ and $U$) over $p$-adic local fields. That is to say that when we have a pair of such groups $G_n\subseteq G_{n+1}$, any…

Representation Theory · Mathematics 2021-06-01 Dor Mezer

We study monoidal categories that enjoy a certain weakening of the rigidity property, namely, the existence of a dualizing object in the sense of Grothendieck and Verdier. We call them Grothendieck-Verdier categories. Notable examples…

Quantum Algebra · Mathematics 2012-04-17 Mitya Boyarchenko , Vladimir Drinfeld

We show in this paper that in the context of graded Lie algebras, all cuspidal character sheaves arise from a nearby-cycle construction followed by a Fourier--Sato transform in a very specific manner. Combined with results of the last two…

Representation Theory · Mathematics 2025-12-29 Wille Liu , Cheng-Chiang Tsai , Kari Vilonen , Ting Xue

In this paper we give a complete classification of cyclically graded semisimple Lie algebras that afford cuspidal character sheaves and determine the support of the cuspidal character sheaves. This constitutes a major step towards the…

Representation Theory · Mathematics 2025-12-24 Wille Liu , Kari Vilonen , Ting Xue

In this paper we introduce a new ingredient, invariant systems of differential equations, to our study of character sheaves on graded Lie algebras. The character sheaves we construct in this paper, together with the ones constructed in…

Representation Theory · Mathematics 2024-10-29 Kari Vilonen , Ting Xue

Given the nilpotent cone of a complex reductive Lie algebra, we consider its equivariant constructible derived category of sheaves with coefficients in an arbitrary field. This category and its subcategory of perverse sheaves play an…

Representation Theory · Mathematics 2012-07-31 Pramod N. Achar , Carl Mautner

A $\mathbf{GL}$-variety is a (typically infinite dimensional) variety modeled on the polynomial representation theory of the general linear group. In previous work, we studied these varieties in characteristic 0. In this paper, we obtain…

Algebraic Geometry · Mathematics 2024-06-12 Arthur Bik , Jan Draisma , Andrew Snowden

In this paper we continue the study of character sheaves on a reductive group G. To each subset of the set of simple reflections in the Weyl group we associate an algebra of the same kind as an Iwahori-Hecke algebra with unequal parameters…

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

We prove that the adjoint equivariant derived category of a reductive group $G$ is equivalent to the appropriately defined monoidal center of the torus-equivariant version of the Hecke category. We use this to give new proofs, independent…

Representation Theory · Mathematics 2024-06-13 Roman Bezrukavnikov , Andrei Ionov , Kostiantyn Tolmachov , Yakov Varshavsky

Assume $\mathbf{G}$ is a connected reductive algebraic group defined over an algebraic closure $\mathbb{K} = \overline{\mathbb{F}}_p$ of the finite field of prime order $p>0$. Furthermore, assume that $F : \mathbf{G} \to \mathbf{G}$ is a…

Representation Theory · Mathematics 2014-10-21 Jay Taylor

We give an explicit description of character sheaves for the symmetric pairs associated to inner involutions of the special linear groups. We make use of the general strategy given in [VX1] and central character consideration. We also…

Representation Theory · Mathematics 2025-03-25 Kari Vilonen , Ting Xue

We construct an extended oriented $(2+\epsilon)$-dimensional topological field theory, the character field theory $X_G$ attached to a affine algebraic group in characteristic zero, which calculates the homology of character varieties of…

Quantum Algebra · Mathematics 2017-05-12 David Ben-Zvi , Sam Gunningham , David Nadler

Let X be an algebraic variety with an action of an algebraic group G. Suppose X has a full exceptional collection of sheaves, and these sheaves are invariant under the action of the group. We construct a semiorthogonal decomposition of…

Algebraic Geometry · Mathematics 2015-05-13 Alexei Elagin

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

In the first part, we construct a new isomorphism between the endomorphism algebra of an induced cuspidal character sheaf and the group algebra of the relative Weyl group involved. We show it differs from the isomorphism of Lusztig by a…

Group Theory · Mathematics 2007-05-23 Cedric Bonnafe

For a split reductive group $G$ over a finite field, we show that the neutral block of its mixed Hecke category with a fixed monodromy under the torus action is monoidally equivalent to the mixed Hecke category of the corresponding…

Representation Theory · Mathematics 2021-08-24 George Lusztig , Zhiwei Yun

We establish a Springer theory for classical symmetric pairs. We give an explicit description of character sheaves in this setting. In particular we determine the cuspidal character sheaves.

Representation Theory · Mathematics 2025-03-25 Kari Vilonen , Ting Xue , with an appendix by Dennis Stanton

We show that some types for supercuspidal representations of tamely ramified $p$-adic groups that appear in Jiu-Kang Yu's work are geometrizable. To do so, we define a function-sheaf dictionary for one-dimensional characters of arbitrary…

Algebraic Geometry · Mathematics 2019-07-04 Clifton Cunningham , David Roe

Moerdijk's site description for equivariant sheaf toposes on open topological groupoids is used to give a proof for the (known, but apparently unpublished) proposition that if H is a strictly full subgroupoid of an open topological groupoid…

Category Theory · Mathematics 2013-07-01 Henrik Forssell

In this note we present a work in progress whose main purpose is to establish a categorified version of sheaf theory. We present a notion of derived categorical sheaves, which is a categorified version of the notion of complexes of sheaves…

Algebraic Geometry · Mathematics 2008-04-09 B. Toën , G. Vezzosi