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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

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

We relate the category of sheaves on alcoves that was constructed in "Sheaves on the alcoves and modular representations I" to the representation theory of reductive algebraic groups. In particular, we show that its indecomposable…

Representation Theory · Mathematics 2020-04-07 Peter Fiebig , Martina Lanini

This paper concerns character sheaves of connected reductive algebraic groups defined over non-Archimedean local fields and their relation with characters of smooth representations. Although character sheaves were devised with characters of…

Representation Theory · Mathematics 2008-12-31 Clifton Cunningham , Hadi Salmasian

We prove a microlocal characterisation of character sheaves on a reductive Lie algebra over an algebraically closed field of sufficiently large positive characteristic: a perverse irreducible G-equivariant sheaf is a character sheaf if and…

Representation Theory · Mathematics 2024-05-14 Tong Zhou

Let G be a reductive connected group over an algebraic closure of a finite field. I define a tensor structure on the category of perverse sheaves on G which are direct sums of unipotent character sheaves in a fixed two-sided cell, in…

Representation Theory · Mathematics 2014-02-18 G. Lusztig

We introduce a class of perverse sheaves on a partial flag manifold of a connected reductive group G defined over a finite field which are equivariant under the action of the group of rational points of G. The definition of this class is…

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

Let $G$ be a connected reductive group over $\kk$, an algebraic closure of a finite field. For an integer $r\ge 1$ let $G_r=G(\kk[\e]/(\e^r))$ viewed as an algebraic group of dimension $r\dim G$ over $\kk$. We show that the character of the…

Representation Theory · Mathematics 2015-11-06 G. Lusztig

We prove that character sheaves have nilpotent singular support in any characteristic, partially extending the work of Mirkovic, Vilonen and independently Ginzburg to positive characteristic. We do this by introducing a category of tame…

Representation Theory · Mathematics 2024-05-17 Kostas I. Psaromiligkos

In this article we formulate and prove the main theorems of the theory of character sheaves on unipotent groups over an algebraically closed field of characteristic p>0. In particular, we show that every admissible pair for such a group G…

Representation Theory · Mathematics 2013-01-08 Mitya Boyarchenko , Vladimir Drinfeld

In this paper we propose a construction of generic character sheaves on reductive groups over finite local rings at even levels, whose characteristic functions are higher Deligne--Lusztig characters when the parameters are generic. We…

Representation Theory · Mathematics 2018-05-01 Zhe Chen

We present various results on disconnected reductive groups, in particular about the characteristic 0 representation theory of such groups over finite fields.

Representation Theory · Mathematics 2020-11-23 F. Digne , J. Michel

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

We consider the rigid monoidal category of character sheaves on a smooth commutative group scheme $G$ over a finite field $k$ and expand the scope of the function-sheaf dictionary from connected commutative algebraic groups to this setting.…

Algebraic Geometry · Mathematics 2015-10-21 Clifton Cunningham , David Roe

The main theme of this paper is establishing the "generalized Springer correspondence" in complete generality that is, for not necessarily connected reductive algebraic groups.

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

We generalize a result by Cunningham-Salmasian to a Mackey-type formula for the compact restriction of a semisimple perverse sheaf produced by parabolic induction from a character sheaf, under certain conditions on the parahoric group used…

Representation Theory · Mathematics 2010-11-09 Pramod N. Achar , Clifton L. R. Cunningham

We prove exactness of parabolic restriction and induction functors for conjugation equivariant sheaves on a reductive group generalizing a well known result of Lusztig who established this property for character sheaves. We propose a…

Representation Theory · Mathematics 2018-10-09 Roman Bezrukavnikov , Alexander Yom Din

We study a class of perverse sheaves on the variety of pairs (P,gU_P) where P runs through a conjugacy class of parabolics in a connected reductive group G and gU_P runs through G/U_P. This is a generalization of the theory of character…

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

Let G be a p-solvable group, P a p-subgroup and chi in Irr(G) such that chi(1)_p \ge |G:P|_p. We prove that the restriction chi_P is a sum of characters induced from subgroups Q\le P such that chi(1)_p=|G:Q|_p. This generalizes previous…

Representation Theory · Mathematics 2021-07-23 Damiano Rossi , Benjamin Sambale

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 Lusztig one by a linear character, and we relate this…

Group Theory · Mathematics 2007-05-23 Cedric Bonnafe