Decomposition Matrix of GL(n,q) and the Heisenberg algebra
|
|
- Ann Miles
- 5 years ago
- Views:
Transcription
1 Decomposition Matrix of GL(n,q) and the Heisenberg algebra Bhama Srinivasan University of Illinois at Chicago mca-13, August 2013 Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
2 G is a nite group. Ordinary representation of G : Representation over a eld of characteristic 0 Modular representation of G : Representation over a eld of characteristic p, p divides jg j. The character of a representation of G over an algebraically closed eld of characteristic 0 (e.g. C) is an "ordinary" character. Brauer character of a modular representation: a complex-valued function on the p-regular elements of G. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
3 p a prime integer K a suciently large eld of characteristic 0 O a complete discrete valuation ring with quotient eld K k residue eld of O, char k=p hama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
4 A representation of G over K is equivalent to a representation over O, and can then be reduced mod p to get a modular representation of G over k. Thus: Compare ordinary and p-modular (Brauer) characters. The decomposition matrix D (over Z) is the transition matrix between ordinary and Brauer characters. Entries of D are decomposition numbers. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
5 In KG -module M, nd lattice, O-module. reduce mod p to get kg -module M D computes composition factor multiplicities of simple kg -modules, in reduction of simple KG or O-module reduced mod p. The matrix D is our main object of study. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
6 G n = GL(n; q), ` a prime not dividing q, e the order of q mod `. Unipotent representations of G n Borel) and are indexed by partitions of n. Example: Steinberg representation are constituents of Ind Gn B (1) (B a End(Ind Gn B (1)) is isomorphic to the Hecke algebra H n of type A. Problem: Unipotent part of Decomposition Matrix of G n. Surprise: The matrix is square. (Fong-BS) Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
7 Dene S n, the q-schur algebra, endomorphism algebra of a sum of permutation representations of the Hecke algebra H n of type A. S n dened over eld of characteristic 0 or ` Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
8 S n G n has Weyl modules, irreducible modules has Specht modules (for unipotent representations), irreducible modules Entries of D are composition multiplicities in either case. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
9 S n over k of characteristic 0, q 2 k, an e-th root of unity. The decomposition matrix is square, has entries the multiplicities of irreducibles in Weyl modules. Known by Varagnolo-Vasserot: transition matrix between a Leclerc-Thibon canonical basis, and a standard basis of a Fock space. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
10 S n over k of characteristic `, q 2 k, an e-th root of unity. Again, the decomposition matrix is square, has entries the multiplicities of irreducibles in Weyl modules. There is the square part of the decomposition matrix of G n, rows indexed by unipotent characters, columns by Brauer characters. (Dipper-James) These two matrices are the same! Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
11 S n over k of characteristic `, q 2 k, an e-th root of unity. Again, the decomposition matrix is square, has entries the multiplicities of irreducibles in Weyl modules. There is the square part of the decomposition matrix of G n, rows indexed by unipotent characters, columns by Brauer characters. (Dipper-James) These two matrices are the same! Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
12 Unipotent characters of G n and Weyl modules of S n are both indexed by partitions of n. Leads to Fock space. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
13 Fock space(level 1): F v = Q(v)u, a vector space over Q(v) with basis u indexed by all partitions. Fix a positive integer e. U v ( sl c e ) acts on this space! Generators e i ; f i are functors on the Fock space: i-induction, i-restriction. Not an irreducible representation, thus we need U v ( gl c e ), so the Heisenberg algebra comes in. Lie algebra c gl e = c sl e + h e. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
14 Fock space(level 1): F v = Q(v)u, a vector space over Q(v) with basis u indexed by all partitions. Fix a positive integer e. U v ( sl c e ) acts on this space! Generators e i ; f i are functors on the Fock space: i-induction, i-restriction. Not an irreducible representation, thus we need U v ( gl c e ), so the Heisenberg algebra comes in. Lie algebra c gl e = c sl e + h e. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
15 The algebra H e has generators hb k jk 2 Z f0gi with relations [B k ; B`] = k 1 v 2nk 1 v 2k k; ` Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
16 (Leclerc-Thibon) Commuting operators V k (k > 1) in H e acting on F v, used to nd new basis: V k (u ) = X ( q) s(=) u where the sum is over all such that is obtained from by adding k e-ribbons, such that the tail of each ribbon is not upon another ribbon. (ribbon= skew-hook, s is the spin.) More generally: V where is a composition: If = f 1 ; 2 ; : : :g then V = V 1 :V 2 : : :. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
17 (Leclerc-Thibon) Commuting operators V k (k > 1) in H e acting on F v, used to nd new basis: V k (u ) = X ( q) s(=) u where the sum is over all such that is obtained from by adding k e-ribbons, such that the tail of each ribbon is not upon another ribbon. (ribbon= skew-hook, s is the spin.) More generally: V where is a composition: If = f 1 ; 2 ; : : :g then V = V 1 :V 2 : : :. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
18 Now regard F v as a vector space over Q l (v) with basis u indexed by all partitions. A n = category of unipotent representations of G n. A = ( n>0k 0 (A n )) Z Q l (v), isomorphic to F v as a Q l (v)-vector space, since A also has a basis indexed by partitions. H e acts on A by the operators V. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
19 Regard A as having a basis indexed by unipotent characters f g where runs through all partitions. Theorem G n = GL(n; q), L = G n GL(k ; q e ). Dene Lusztig maps L k : K 0 (A n )! K 0 (A n+ke ) by : [ ]! [R G n+ke L ( (k) )]. Then L k coincides with the operator V k Deligne-Lusztig induction. specialized at v = 1. Here R G n+ke L More generally, dene L, a partition of k. This coincides with V. is Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
20 fg n = GL(n; F q ), P = f L n U f G n a parabolic subgroup, L n G n the group of F q -rational points of L f n. X L = Deligne-Lusztig G n -variety-l n, dened as X L = fg 2 G f n jg 1 F (g) 2 Ug. We have a complex R c (X L ), gives rise to a functor D b (Q l L n mod)! D b (Q l G n mod) (Bonnafe-Rouquier, [Publ. Math. IHES 97 (2003), 1-59]) Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
21 Set v = 1. Categorify V k by a Deligne-Lusztig functor. Category B = n>0d b (Q l G n mod) (unipotent representations). Functor S k : D b (Q l G n mod)! D b (Q l G n+ke mod) is dened by: C! R c (X n ) L (C K Ln (k)). K (k) is a complex in D b (Q l (GL(k ; q e ) mod) with one term the trivial representation of GL(k ; q e ), parametrized by the partition (k). Note L n = G n GL(k ; q e ) G n+ke. So S k maps B to B. The functor S k categories V k. Similarly have S. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
22 Remark. Licata and Savage study actions of the Heisenberg algebra on the category we have denoted by A. Their operators are ordinary induction and restriction. Remark. Shan and Vasserot have dened actions of H e on Fock space of higher level by operators analogous to V, L. Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
23 (Geck) Decomposition numbers for GL n (q), ` large known via the q-schur algebra S n Not known: Decomposition numbers for GL n (q), all ` Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
24 References S.Ariki, Graded q-schur algebras, Preprint, arxiv: R.Dipper, G.James, Proc. London Math. Soc. 59 (1989), B.Leclerc, J-Y. Thibon, Canonical bases of q-deformed Fock spaces, Int. math. Res. Notices 9 (1996), A.Licata, A.Savage, Hecke algebras, nite general linear groups, Heisenberg categorication, arxiv P.Shan, E.Vasserot, Heisenberg algebras and rational DAHA, JAMS 25 (2012), Bhama Srinivasan (University of Illinois at Chicago) Heisenberg algebra mca-13, August / 21
Modular representations of symmetric groups: An Overview
Modular representations of symmetric groups: An Overview Bhama Srinivasan University of Illinois at Chicago Regina, May 2012 Bhama Srinivasan (University of Illinois at Chicago) Modular Representations
More information`-modular Representations of Finite Reductive Groups
`-modular Representations of Finite Reductive Groups Bhama Srinivasan University of Illinois at Chicago AIM, June 2007 Bhama Srinivasan (University of Illinois at Chicago) Modular Representations AIM,
More informationON CRDAHA AND FINITE GENERAL LINEAR AND UNITARY GROUPS. Dedicated to the memory of Robert Steinberg. 1. Introduction
ON CRDAHA AND FINITE GENERAL LINEAR AND UNITARY GROUPS BHAMA SRINIVASAN Abstract. We show a connection between Lusztig induction operators in finite general linear and unitary groups and parabolic induction
More informationFINITE GROUPS OF LIE TYPE AND THEIR
FINITE GROUPS OF LIE TYPE AND THEIR REPRESENTATIONS LECTURE IV Gerhard Hiss Lehrstuhl D für Mathematik RWTH Aachen University Groups St Andrews 2009 in Bath University of Bath, August 1 15, 2009 CONTENTS
More informationRECOLLECTION THE BRAUER CHARACTER TABLE
RECOLLECTION REPRESENTATIONS OF FINITE GROUPS OF LIE TYPE LECTURE III: REPRESENTATIONS IN NON-DEFINING CHARACTERISTICS AIM Classify all irreducible representations of all finite simple groups and related
More informationTHE 2-MODULAR DECOMPOSITION MATRICES OF THE SYMMETRIC GROUPS S 15, S 16, AND S 17
THE 2-MODULAR DECOMPOSITION MATRICES OF THE SYMMETRIC GROUPS S 15, S 16, AND S 17 Abstract. In this paper the 2-modular decomposition matrices of the symmetric groups S 15, S 16, and S 17 are determined
More informationMODULAR REPRESENTATIONS, OLD AND NEW. To the memory of Harish-Chandra. 1. Introduction
1 MODULAR REPRESENTATIONS, OLD AND NEW BHAMA SRINIVASAN To the memory of Harish-Chandra 1. Introduction The art of story telling is very old in India, as is evidenced by the great epics Ramayana and Mahabharata.
More informationTHREE CASES AN EXAMPLE: THE ALTERNATING GROUP A 5
THREE CASES REPRESENTATIONS OF FINITE GROUPS OF LIE TYPE LECTURE II: DELIGNE-LUSZTIG THEORY AND SOME APPLICATIONS Gerhard Hiss Lehrstuhl D für Mathematik RWTH Aachen University Summer School Finite Simple
More informationarxiv: v1 [math.rt] 11 Sep 2009
FACTORING TILTING MODULES FOR ALGEBRAIC GROUPS arxiv:0909.2239v1 [math.rt] 11 Sep 2009 S.R. DOTY Abstract. Let G be a semisimple, simply-connected algebraic group over an algebraically closed field of
More informationUnipotent Brauer character values of GL(n, F q ) and the forgotten basis of the Hall algebra
Unipotent Brauer character values of GL(n, F q ) and the forgotten basis of the Hall algebra Jonathan Brundan Abstract We give a formula for the values of irreducible unipotent p-modular Brauer characters
More informationTowers of algebras categorify the Heisenberg double
Towers of algebras categorify the Heisenberg double Joint with: Oded Yacobi (Sydney) Alistair Savage University of Ottawa Slides available online: AlistairSavage.ca Preprint: arxiv:1309.2513 Alistair Savage
More informationCharacter sheaves and modular generalized Springer correspondence Part 2: The generalized Springer correspondence
Character sheaves and modular generalized Springer correspondence Part 2: The generalized Springer correspondence Anthony Henderson (joint with Pramod Achar, Daniel Juteau, Simon Riche) University of Sydney
More information294 Meinolf Geck In 1992, Lusztig [16] addressed this problem in the framework of his theory of character sheaves and its application to Kawanaka's th
Doc. Math. J. DMV 293 On the Average Values of the Irreducible Characters of Finite Groups of Lie Type on Geometric Unipotent Classes Meinolf Geck Received: August 16, 1996 Communicated by Wolfgang Soergel
More information0 A. ... A j GL nj (F q ), 1 j r
CHAPTER 4 Representations of finite groups of Lie type Let F q be a finite field of order q and characteristic p. Let G be a finite group of Lie type, that is, G is the F q -rational points of a connected
More informationCharacter Sheaves and GGGRs
Character Sheaves and GGGRs Jay Taylor Technische Universität Kaiserslautern Algebra Seminar University of Georgia 24th March 2014 Jay Taylor (TU Kaiserslautern) Character Sheaves Georgia, March 2014 1
More informationDUALITY, CENTRAL CHARACTERS, AND REAL-VALUED CHARACTERS OF FINITE GROUPS OF LIE TYPE
DUALITY, CENTRAL CHARACTERS, AND REAL-VALUED CHARACTERS OF FINITE GROUPS OF LIE TYPE C. RYAN VINROOT Abstract. We prove that the duality operator preserves the Frobenius- Schur indicators of characters
More informationA CATEGORIFICATION OF INTEGRAL SPECHT MODULES. 1. Introduction
A CATEGORIFICATION OF INTEGRAL SPECHT MODULES MIKHAIL KHOVANOV, VOLODYMYR MAZORCHUK, AND CATHARINA STROPPEL Abstract. We suggest a simple definition for categorification of modules over rings and illustrate
More informationInduced Representations and Frobenius Reciprocity. 1 Generalities about Induced Representations
Induced Representations Frobenius Reciprocity Math G4344, Spring 2012 1 Generalities about Induced Representations For any group G subgroup H, we get a restriction functor Res G H : Rep(G) Rep(H) that
More informationModular representation theory
Modular representation theory 1 Denitions for the study group Denition 1.1. Let A be a ring and let F A be the category of all left A-modules. The Grothendieck group of F A is the abelian group dened by
More informationCharacter sheaves and modular generalized Springer correspondence Part 2: The generalized Springer correspondence
Character sheaves and modular generalized Springer correspondence Part 2: The generalized Springer correspondence Anthony Henderson (joint with Pramod Achar, Daniel Juteau, Simon Riche) University of Sydney
More informationTensor products and restrictions in type A
[Page 1] Tensor products and restrictions in type A Jonathan Brundan and Alexander S. Kleshchev Abstract. The goal of this article is to give an exposition of some recent results on tensor products and
More informationCity Research Online. Permanent City Research Online URL:
Linckelmann, M. & Schroll, S. (2005). A two-sided q-analogue of the Coxeter complex. Journal of Algebra, 289(1), 128-134. doi: 10.1016/j.jalgebra.2005.03.026,
More informationRepresentations of algebraic groups and their Lie algebras Jens Carsten Jantzen Lecture III
Representations of algebraic groups and their Lie algebras Jens Carsten Jantzen Lecture III Lie algebras. Let K be again an algebraically closed field. For the moment let G be an arbitrary algebraic group
More informationCategorification, Lie algebras and Topology
Categorification, Lie algebras and Topology Ben Webster Northeastern University/University of Oregon June 17, 2011 Ben Webster (Northeastern/Oregon) Categorification, Lie algebras and Topology June 17,
More informationFAMILIES OF IRREDUCIBLE REPRESENTATIONS OF S 2 S 3
FAMILIES OF IRREDUCIBLE REPRESENTATIONS OF S S 3 JAY TAYLOR We would like to consider the representation theory of the Weyl group of type B 3, which is isomorphic to the wreath product S S 3 = (S S S )
More informationOn the classication of algebras
Technische Universität Carolo-Wilhelmina Braunschweig Institut Computational Mathematics On the classication of algebras Morten Wesche September 19, 2016 Introduction Higman (1950) published the papers
More informationReducibility of generic unipotent standard modules
Journal of Lie Theory Volume?? (??)???? c?? Heldermann Verlag 1 Version of March 10, 011 Reducibility of generic unipotent standard modules Dan Barbasch and Dan Ciubotaru Abstract. Using Lusztig s geometric
More informationRepresentations of algebraic groups and their Lie algebras Jens Carsten Jantzen Lecture I
Representations of algebraic groups and their Lie algebras Jens Carsten Jantzen Lecture I Set-up. Let K be an algebraically closed field. By convention all our algebraic groups will be linear algebraic
More informationSymmetric functions and the Fock space
Symmetric functions and the Fock space representation of Í Õ Ð Ò µ (Lectures at the Isaac Newton Institute, Cambridge) Bernard LECLERC June 00 Dedicated to Denis UGLOV (968 999) Introduction Throughout
More informationON LOWER BOUNDS FOR THE DIMENSIONS OF PROJECTIVE MODULES FOR FINITE SIMPLE GROUPS. A.E. Zalesski
ON LOWER BOUNDS FOR THE DIMENSIONS OF PROJECTIVE MODULES FOR FINITE SIMPLE GROUPS A.E. Zalesski Group rings and Young-Baxter equations Spa, Belgium, June 2017 1 Introduction Let G be a nite group and p
More informationGoals of this document This document tries to explain a few algorithms from Lie theory that would be useful to implement. I tried to include explanati
Representation Theory Issues For Sage Days 7 Goals of this document This document tries to explain a few algorithms from Lie theory that would be useful to implement. I tried to include explanations of
More informationIrreducible Representations of symmetric group S n
Irreducible Representations of symmetric group S n Yin Su 045 Good references: ulton Young tableaux with applications to representation theory and geometry ulton Harris Representation thoery a first course
More informationExercises on chapter 1
Exercises on chapter 1 1. Let G be a group and H and K be subgroups. Let HK = {hk h H, k K}. (i) Prove that HK is a subgroup of G if and only if HK = KH. (ii) If either H or K is a normal subgroup of G
More informationA NOTE ON SPLITTING FIELDS OF REPRESENTATIONS OF FINITE
A NOTE ON SPLITTING FIELDS OF REPRESENTATIONS OF FINITE GROUPS BY Let @ be a finite group, and let x be the character of an absolutely irreducible representation of @ An algebraic number field K is defined
More informationIVAN LOSEV. Lemma 1.1. (λ) O. Proof. (λ) is generated by a single vector, v λ. We have the weight decomposition (λ) =
LECTURE 7: CATEGORY O AND REPRESENTATIONS OF ALGEBRAIC GROUPS IVAN LOSEV Introduction We continue our study of the representation theory of a finite dimensional semisimple Lie algebra g by introducing
More informationSEMISIMPLE SYMPLECTIC CHARACTERS OF FINITE UNITARY GROUPS
SEMISIMPLE SYMPLECTIC CHARACTERS OF FINITE UNITARY GROUPS BHAMA SRINIVASAN AND C. RYAN VINROOT Abstract. Let G = U(2m, F q 2) be the finite unitary group, with q the power of an odd prime p. We prove that
More informationCharacter Sheaves and GGGRs
and GGGRs Jay Taylor Technische Universität Kaiserslautern Global/Local Conjectures in Representation Theory of Finite Groups Banff, March 2014 Jay Taylor (TU Kaiserslautern) Character Sheaves Banff, March
More informationON AN INFINITE-DIMENSIONAL GROUP OVER A FINITE FIELD. A. M. Vershik, S. V. Kerov
ON AN INFINITE-DIMENSIONAL GROUP OVER A FINITE FIELD A. M. Vershik, S. V. Kerov Introduction. The asymptotic representation theory studies the behavior of representations of large classical groups and
More informationQUALIFYING EXAM IN ALGEBRA August 2011
QUALIFYING EXAM IN ALGEBRA August 2011 1. There are 18 problems on the exam. Work and turn in 10 problems, in the following categories. I. Linear Algebra 1 problem II. Group Theory 3 problems III. Ring
More informationOn splitting of the normalizer of a maximal torus in groups of Lie type
On splitting of the normalizer of a maximal torus in groups of Lie type Alexey Galt 07.08.2017 Example 1 Let G = SL 2 ( (F p ) be the ) special linear group of degree 2 over F p. λ 0 Then T = { 0 λ 1,
More informationMaximal strings in the crystal graph of spin representations Of the symmetric and alternating groups
Maximal strings in the crystal graph of spin representations Of the symmetric and alternating groups Hussam Arisha and Mary Schaps Abstract: We define block-reduced version of the crystal graph of spin
More informationRepresentation theory through the lens of categorical actions: part III
Reminders Representation theory through the lens of categorical actions: part III University of Virginia June 17, 2015 Reminders Definition A g-action on an additive category C consists of: A direct sum
More informationPresenting and Extending Hecke Endomorphism Algebras
Presenting and Extending Hecke Endomorphism Algebras Jie Du University of New South Wales Shanghai Conference on Representation Theory 7-11 December 2015 1 / 27 The Hecke Endomorphism Algebra The (equal
More informationarxiv:math/ v3 [math.rt] 2 Jun 2006
MODULAR PRINCIPAL SERIES REPRESENTATIONS arxiv:math/0603046v3 [math.rt] 2 Jun 2006 MEINOLF GECK Abstract. We present a classification of the modular principal series representations of a finite group of
More informationSPHERICAL UNITARY REPRESENTATIONS FOR REDUCTIVE GROUPS
SPHERICAL UNITARY REPRESENTATIONS FOR REDUCTIVE GROUPS DAN CIUBOTARU 1. Classical motivation: spherical functions 1.1. Spherical harmonics. Let S n 1 R n be the (n 1)-dimensional sphere, C (S n 1 ) the
More informationSign elements in symmetric groups
Dept. of Mathematical Sciences University of Copenhagen, Denmark Nagoya, September 4, 2008 Introduction Work in progress Question by G. Navarro about characters in symmetric groups, related to a paper
More informationLECTURE 11: SOERGEL BIMODULES
LECTURE 11: SOERGEL BIMODULES IVAN LOSEV Introduction In this lecture we continue to study the category O 0 and explain some ideas towards the proof of the Kazhdan-Lusztig conjecture. We start by introducing
More informationDecomposition numbers for generic Iwahori-Hecke algebras of non-crystallographic type
Decomposition numbers for generic Iwahori-Hecke algebras of non-crystallographic type Jürgen Müller IWR der Universität Heidelberg Im Neuenheimer Feld 368 D 69120 Heidelberg Abstract In this note we compute
More informationON SOME PARTITIONS OF A FLAG MANIFOLD. G. Lusztig
ON SOME PARTITIONS OF A FLAG MANIFOLD G. Lusztig Introduction Let G be a connected reductive group over an algebraically closed field k of characteristic p 0. Let W be the Weyl group of G. Let W be the
More informationRepresentations Are Everywhere
Representations Are Everywhere Nanghua Xi Member of Chinese Academy of Sciences 1 What is Representation theory Representation is reappearance of some properties or structures of one object on another.
More informationOn the geometric Langlands duality
On the geometric Langlands duality Peter Fiebig Emmy Noether Zentrum Universität Erlangen Nürnberg Schwerpunkttagung Bad Honnef April 2010 Outline This lecture will give an overview on the following topics:
More informationCHARACTER SHEAVES ON UNIPOTENT GROUPS IN CHARACTERISTIC p > 0. Mitya Boyarchenko Vladimir Drinfeld. University of Chicago
arxiv:1301.0025v1 [math.rt] 31 Dec 2012 CHARACTER SHEAVES ON UNIPOTENT GROUPS IN CHARACTERISTIC p > 0 Mitya Boyarchenko Vladimir Drinfeld University of Chicago Overview These are slides for a talk given
More informationAlgebra Exam Topics. Updated August 2017
Algebra Exam Topics Updated August 2017 Starting Fall 2017, the Masters Algebra Exam will have 14 questions. Of these students will answer the first 8 questions from Topics 1, 2, and 3. They then have
More informationQuantum supergroups and canonical bases
Quantum supergroups and canonical bases Sean Clark University of Virginia Dissertation Defense April 4, 2014 WHAT IS A QUANTUM GROUP? A quantum group is a deformed universal enveloping algebra. WHAT IS
More informationQuantum linear groups and representations of GL n (F q )
Quantum linear groups and representations of GL n (F q ) Jonathan Brundan Richard Dipper Department of Mathematics Mathematisches Institut B University of Oregon Universität Stuttgart Eugene, OR 97403
More informationREPRESENTATIONS OF S n AND GL(n, C)
REPRESENTATIONS OF S n AND GL(n, C) SEAN MCAFEE 1 outline For a given finite group G, we have that the number of irreducible representations of G is equal to the number of conjugacy classes of G Although
More informationALGEBRAIC GROUPS J. WARNER
ALGEBRAIC GROUPS J. WARNER Let k be an algebraically closed field. varieties unless otherwise stated. 1. Definitions and Examples For simplicity we will work strictly with affine Definition 1.1. An algebraic
More informationREPRESENTATIONS OF FINITE GROUPS OF LIE TYPE: EXERCISES. Notation. 1. GL n
REPRESENTATIONS OF FINITE GROUPS OF LIE TYPE: EXERCISES ZHIWEI YUN Fix a prime number p and a power q of p. k = F q ; k d = F q d. ν n means ν is a partition of n. Notation Conjugacy classes 1. GL n 1.1.
More informationMAXIMAL STRINGS IN THE CRYSTAL GRAPH OF SPIN REPRESENTATIONS OF THE SYMMETRIC AND ALTERNATING GROUPS
MAXIMAL STRINGS IN THE CRYSTAL GRAPH OF SPIN REPRESENTATIONS OF THE SYMMETRIC AND ALTERNATING GROUPS HUSSAM ARISHA AND MARY SCHAPS Abstract. We define a block-reduced version of the crystal graph of spin
More informationPrimitive Ideals and Unitarity
Primitive Ideals and Unitarity Dan Barbasch June 2006 1 The Unitary Dual NOTATION. G is the rational points over F = R or a p-adic field, of a linear connected reductive group. A representation (π, H)
More informationGALOIS GROUP ACTION AND JORDAN DECOMPOSITION OF CHARACTERS OF FINITE REDUCTIVE GROUPS WITH CONNECTED CENTER
GALOIS GROUP ACTION AND JORDAN DECOMPOSITION OF CHARACTERS OF FINITE REDUCTIVE GROUPS WITH CONNECTED CENTER BHAMA SRINIVASAN AND C. RYAN VINROOT Abstract. Let G be a connected reductive group with connected
More informationCover Page. The handle holds various files of this Leiden University dissertation.
Cover Page The handle http://hdl.handle.net/1887/22043 holds various files of this Leiden University dissertation. Author: Anni, Samuele Title: Images of Galois representations Issue Date: 2013-10-24 Chapter
More informationLecture 4: LS Cells, Twisted Induction, and Duality
Lecture 4: LS Cells, Twisted Induction, and Duality B. Binegar Department of Mathematics Oklahoma State University Stillwater, OK 74078, USA Nankai Summer School in Representation Theory and Harmonic Analysis
More informationLifting to non-integral idempotents
Journal of Pure and Applied Algebra 162 (2001) 359 366 www.elsevier.com/locate/jpaa Lifting to non-integral idempotents Georey R. Robinson School of Mathematics and Statistics, University of Birmingham,
More informationSELF-EQUIVALENCES OF THE DERIVED CATEGORY OF BRAUER TREE ALGEBRAS WITH EXCEPTIONAL VERTEX
An. Şt. Univ. Ovidius Constanţa Vol. 9(1), 2001, 139 148 SELF-EQUIVALENCES OF THE DERIVED CATEGORY OF BRAUER TREE ALGEBRAS WITH EXCEPTIONAL VERTEX Alexander Zimmermann Abstract Let k be a field and A be
More informationarxiv: v1 [math.rt] 14 Nov 2007
arxiv:0711.2128v1 [math.rt] 14 Nov 2007 SUPPORT VARIETIES OF NON-RESTRICTED MODULES OVER LIE ALGEBRAS OF REDUCTIVE GROUPS: CORRIGENDA AND ADDENDA ALEXANDER PREMET J. C. Jantzen informed me that the proof
More informationREPRESENTATION THEORY, LECTURE 0. BASICS
REPRESENTATION THEORY, LECTURE 0. BASICS IVAN LOSEV Introduction The aim of this lecture is to recall some standard basic things about the representation theory of finite dimensional algebras and finite
More informationLECTURE 20: KAC-MOODY ALGEBRA ACTIONS ON CATEGORIES, II
LECTURE 20: KAC-MOODY ALGEBRA ACTIONS ON CATEGORIES, II IVAN LOSEV 1. Introduction 1.1. Recap. In the previous lecture we have considered the category C F := n 0 FS n -mod. We have equipped it with two
More informationTHE BRAUER HOMOMORPHISM AND THE MINIMAL BASIS FOR CENTRES OF IWAHORI-HECKE ALGEBRAS OF TYPE A. Andrew Francis
THE BRAUER HOMOMORPHISM AND THE MINIMAL BASIS FOR CENTRES OF IWAHORI-HECKE ALGEBRAS OF TYPE A Andrew Francis University of Western Sydney - Hawkesbury, Locked Bag No. 1, Richmond NSW 2753, Australia a.francis@uws.edu.au
More informationExternal Littelmann Paths of Kashiwara Crystals of Type A ran
Bar-Ilan University Combinatorics and Representation Theory July 23-27, 2018 ran Table of Contents 1 2 3 4 5 6 ran Crystals B(Λ) Let G over C be an affine Lie algebra of type A rank e. Let Λ be a dominant
More informationCHARACTER SHEAVES ON UNIPOTENT GROUPS IN CHARACTERISTIC p > 0. Mitya Boyarchenko Vladimir Drinfeld. University of Chicago
CHARACTER SHEAVES ON UNIPOTENT GROUPS IN CHARACTERISTIC p > 0 Mitya Boyarchenko Vladimir Drinfeld University of Chicago Some historical comments A geometric approach to representation theory for unipotent
More informationEndomorphism rings of permutation modules
Endomorphism rings of permutation modules Natalie Naehrig Lehrstuhl D für Mathematik RWTH Aachen University naehrig@math.rwth-aachen.de December 9, 2009 Abstract Let k be an algebraically closed field
More informationDecomposition numbers and canonical bases
Decomposition numbers and canonical bases Bernard Leclerc arxiv:math/9902006v1 [math.qa] 1 Feb 1999 Département de Mathématiques, Université de Caen, 14032 Caen cedex, France. leclerc@math.unicaen.fr http://matin.math.unicaen.fr/~leclerc
More informationON THE MODIFIED MOD p LOCAL LANGLANDS CORRESPONDENCE FOR GL 2 (Q l )
ON THE MODIFIED MOD p LOCAL LANGLANDS CORRESPONDENCE FOR GL 2 (Q l ) DAVID HELM We give an explicit description of the modified mod p local Langlands correspondence for GL 2 (Q l ) of [EH], Theorem 5.1.5,
More informationCATEGORICAL sl 2 ACTIONS
CATEGORICAL sl 2 ACTIONS ANTHONY LICATA 1. Introduction 1.1. Actions of sl 2 on categories. A action of sl 2 on a finite-dimensional C-vector space V consists of a direct sum decomposition V = V (λ) into
More informationHigher Schur-Weyl duality for cyclotomic walled Brauer algebras
Higher Schur-Weyl duality for cyclotomic walled Brauer algebras (joint with Hebing Rui) Shanghai Normal University December 7, 2015 Outline 1 Backgroud 2 Schur-Weyl duality between general linear Lie algebras
More informationTHE S 1 -EQUIVARIANT COHOMOLOGY RINGS OF (n k, k) SPRINGER VARIETIES
Horiguchi, T. Osaka J. Math. 52 (2015), 1051 1062 THE S 1 -EQUIVARIANT COHOMOLOGY RINGS OF (n k, k) SPRINGER VARIETIES TATSUYA HORIGUCHI (Received January 6, 2014, revised July 14, 2014) Abstract The main
More informationOn certain family of B-modules
On certain family of B-modules Piotr Pragacz (IM PAN, Warszawa) joint with Witold Kraśkiewicz with results of Masaki Watanabe Issai Schur s dissertation (Berlin, 1901): classification of irreducible polynomial
More informationDESCRIPTION OF SIMPLE MODULES FOR SCHUR SUPERALGEBRA S(2j2)
DESCRIPTION OF SIMPLE MODULES FOR SCHUR SUPERALGEBRA S(22) A.N. GRISHKOV AND F. MARKO Abstract. The goal of this paper is to describe explicitly simple modules for Schur superalgebra S(22) over an algebraically
More informationAn example of higher representation theory
An example of higher representation theory Geordie Williamson Max Planck Institute, Bonn Geometric and categorical representation theory, Mooloolaba, December 2015. First steps in representation theory.
More informationRESEARCH STATEMENT. Contents
RESEARCH STATEMENT VINOTH NANDAKUMAR Contents 1. Modular representation theory, and categorification 1 2. Combinatorial bijections arising from Springer theory 3 3. Quantum groups, category O 5 References
More informationCENTRAL CHARACTERS FOR SMOOTH IRREDUCIBLE MODULAR REPRESENTATIONS OF GL 2 (Q p ) Laurent Berger
CENTRAL CHARACTERS FOR SMOOTH IRREDUCIBLE MODULAR REPRESENTATIONS OF GL 2 (Q p by Laurent Berger To Francesco Baldassarri, on the occasion of his 60th birthday Abstract. We prove that every smooth irreducible
More informationSOURCE ALGEBRAS AND SOURCE MODULES J. L. Alperin, Markus Linckelmann, Raphael Rouquier May 1998 The aim of this note is to give short proofs in module
SURCE ALGEBRAS AND SURCE MDULES J. L. Alperin, Markus Linckelmann, Raphael Rouquier May 1998 The aim of this note is to give short proofs in module theoretic terms of two fundamental results in block theory,
More informationWhat elliptic cohomology might have to do with other generalized Schubert calculi
What elliptic cohomology might have to do with other generalized Schubert calculi Gufang Zhao University of Massachusetts Amherst Equivariant generalized Schubert calculus and its applications Apr. 28,
More informationTHE 7-MODULAR DECOMPOSITION MATRICES OF THE SPORADIC O NAN GROUP
THE 7-MODULAR DECOMPOSITION MATRICES OF THE SPORADIC O NAN GROUP ANNE HENKE, GERHARD HISS, AND JÜRGEN MÜLLER Abstract. The determination of the modular character tables of the sporadic O Nan group, its
More informationNOTES ON MODULAR REPRESENTATIONS OF p-adic GROUPS, AND THE LANGLANDS CORRESPONDENCE
NOTES ON MODULAR REPRESENTATIONS OF p-adic GROUPS, AND THE LANGLANDS CORRESPONDENCE DIPENDRA PRASAD These are expanded notes of some lectures given by the author for a workshop held at the Indian Statistical
More informationSOLVABLE FUSION CATEGORIES AND A CATEGORICAL BURNSIDE S THEOREM
SOLVABLE FUSION CATEGORIES AND A CATEGORICAL BURNSIDE S THEOREM PAVEL ETINGOF The goal of this talk is to explain the classical representation-theoretic proof of Burnside s theorem in finite group theory,
More informationCharacter values and decomposition matrices of symmetric groups
Character values and decomposition matrices of symmetric groups Mark Wildon Abstract The relationships between the values taken by ordinary characters of symmetric groups are exploited to prove two theorems
More informationA RELATION BETWEEN SCHUR P AND S. S. Leidwanger. Universite de Caen, CAEN. cedex FRANCE. March 24, 1997
A RELATION BETWEEN SCHUR P AND S FUNCTIONS S. Leidwanger Departement de Mathematiques, Universite de Caen, 0 CAEN cedex FRANCE March, 997 Abstract We dene a dierential operator of innite order which sends
More informationAlgebras and regular subgroups. Marco Antonio Pellegrini. Ischia Group Theory Joint work with Chiara Tamburini
Joint work with Chiara Tamburini Università Cattolica del Sacro Cuore Ischia Group Theory 2016 Affine group and Regular subgroups Let F be any eld. We identify the ane group AGL n (F) with the subgroup
More informationTWO-ROWED A-TYPE HECKE ALGEBRA REPRESENTATIONS AT ROOTS OF UNITY
1 TWO-ROWED A-TYPE HECKE ALGEBRA REPRESENTATIONS AT ROOTS OF UNITY Trevor Alan Welsh Faculty of Mathematical Studies University of Southampton Southampton SO17 1BJ U.K. Lehrstuhl II für Mathematik Universität
More informationEQUIVARIANT COHOMOLOGY. p : E B such that there exist a countable open covering {U i } i I of B and homeomorphisms
EQUIVARIANT COHOMOLOGY MARTINA LANINI AND TINA KANSTRUP 1. Quick intro Let G be a topological group (i.e. a group which is also a topological space and whose operations are continuous maps) and let X be
More informationR-matrices, affine quantum groups and applications
R-matrices, affine quantum groups and applications From a mini-course given by David Hernandez at Erwin Schrödinger Institute in January 2017 Abstract R-matrices are solutions of the quantum Yang-Baxter
More informationList of abstracts. Workshop: Gradings and Decomposition Numbers, September 24-28, All lectures will take place in room V57.02.
List of abstracts Workshop: Gradings and Decomposition Numbers, September 24-28, 2012 All lectures will take place in room V57.02. Monday 13:35-14:25 Alexander Kleshchev, Part 1 Title: Representations
More informationON THE CLASSIFICATION OF RANK 1 GROUPS OVER NON ARCHIMEDEAN LOCAL FIELDS
ON THE CLASSIFICATION OF RANK 1 GROUPS OVER NON ARCHIMEDEAN LOCAL FIELDS LISA CARBONE Abstract. We outline the classification of K rank 1 groups over non archimedean local fields K up to strict isogeny,
More informationWHITTAKER MODELS AND THE INTEGRAL BERNSTEIN CENTER FOR GL n
WHITTAKER MODELS AND THE INTEGRAL BERNSTEIN CENTER OR GL n DAVID HELM Abstract. We establish integral analogues of results of Bushnell and Henniart [BH] for spaces of Whittaker functions arising from the
More informationSpherical varieties and arc spaces
Spherical varieties and arc spaces Victor Batyrev, ESI, Vienna 19, 20 January 2017 1 Lecture 1 This is a joint work with Anne Moreau. Let us begin with a few notations. We consider G a reductive connected
More informationLECTURE 4: REPRESENTATION THEORY OF SL 2 (F) AND sl 2 (F)
LECTURE 4: REPRESENTATION THEORY OF SL 2 (F) AND sl 2 (F) IVAN LOSEV In this lecture we will discuss the representation theory of the algebraic group SL 2 (F) and of the Lie algebra sl 2 (F), where F is
More informationFOULKES MODULES AND DECOMPOSITION NUMBERS OF THE SYMMETRIC GROUP
FOULKES MODULES AND DECOMPOSITION NUMBERS OF THE SYMMETRIC GROUP EUGENIO GIANNELLI AND MARK WILDON Abstract. The decomposition matrix of a finite group in prime characteristic p records the multiplicities
More informationIrreducible subgroups of algebraic groups
Irreducible subgroups of algebraic groups Martin W. Liebeck Department of Mathematics Imperial College London SW7 2BZ England Donna M. Testerman Department of Mathematics University of Lausanne Switzerland
More information