Questions tagged [hecke-algebras]
The hecke-algebras tag has no usage guidance.
149
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Hecke algebra $\mathcal{H}(K_1\backslash \mathrm{GL}_n(\mathbb{F})/K_1)$
$\DeclareMathOperator\GL{GL}$Let $\mathbb{F}$ be a non-Archimedean local field. Let $\mathcal{O}$ be its ring of integers, and let $\frak{m}$ be its maximal ideal Let $\GL_n(\mathcal{O})$ be the group ...
10
votes
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answer
321
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How is Taylor-Wiles patching "horizontal Iwasawa theory"?
I have recently been reading into the proof of modularity of semistable elliptic curves, in particular (what is now known as) the Taylor-Wiles patching argument used to prove the $R=T$ theorem in the ...
3
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0
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134
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Taylor-Wiles systems for higher dimensional deformation rings
Let $R$ be a deformation ring and $M$ be a finitely generated $R$-module.
A strategy for proving the theorems $R=T$ is to associate with $(R,M)$ a Taylor-Wiles system denoted $(R_{Q},M_{Q})$. Here I'm ...
1
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64
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Automorphisms of Iwahori/affine Hecke algebras
Has there been any serious study of automorphisms of extended affine Hecke algebras? Has anyone determined the automorphism group of say, type A extended affine Hecke algebras? I ask because the ...
3
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101
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List of techniques that have been used to prove topological properties of locus in the deformation ring or the Hecke algebra
My question is maybe going to be a bit vague. My apologies if so.
The setting:
Let $\overline{\rho}$ be a residual representation and $R$ be a deformation ring of $\overline{\rho}$.
Let $\mathbb{T}$ ...
4
votes
2
answers
267
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Parabolic induction, and tensoring (Iwahori/affine) Hecke algebras
In several places, such as [1] and [2], it seems to be implicitly known that (normalized) parabolic induction corresponds to tensoring affine Hecke algebras. I say implicitly because both [1] and [2] ...
4
votes
1
answer
198
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Eigenvalue of Iwahori Hecke Algebra element for the Steinberg
In Iwahori-Matsumoto's paper the Iwahori Hecke Algebra for $G=GL_n(F)$ is generated by $X_{s_0}, X_{s_i},i\in\{0,...,n-1\}$ and $ X_{\rho}$ with the relations:
$
1) (X_{s_{i}}-q)(X_{s_{i}}+1)=0\:,\;\;...
0
votes
1
answer
70
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Analog of self-conjugate representation of symmetric group for Hecke algebra
Consider a symmetric group $S_n$. It is generated by generators $\sigma_1\dotsc\sigma_{n-1}$ that satisfy the following relations:
Square relations: $\sigma_k^2=1,\qquad k=1\ldots n-1$.
Braid ...
2
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0
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A list of $R=T$ theorems for $\mathbf{GSp}_4$
I know of only two cases of theorem $R=T$ where $T$ is a Hecke algebra acting on an automorphic forms (or representations) space of $\mathbf{GSp}_4$, the first one was proved by A.Genestier and J....
4
votes
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100
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Property of simplicity and semi-simplicity under base change of base field
Suppose $K$ is a field of characteristic $0$ and $A$ is a $K$-algebra. Let $F$ be a field extension of $K$ and let $M$ be an $A$-module. What can we say about simplicity or semi-simplicity of $A_F$-...
4
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148
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Spectral projection of an eigenvalue associated to a generator of Hecke algebras
In his paper "Hecke Algebras of type $A_n$ (Inv. Math. 1988, EUDML link) and subfactors", in section 2 "Orthogonal representations...", Wenzl takes the usual third relation of a ...
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0
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57
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Admissibility of representations induced from Hecke algebra for covering groups
Assume $G$ is a semisimple algebraic group and $B$ is an Iwahori subgroup. Let $(r,E)$ be a representation of $H(G,B)$ which is an Iwahori-Hecke algebra, then Borel proved that $C_{c}(G/B)\otimes_{H}E$...
5
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396
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p-adic Hecke operators in the Iwahori-Hecke algebra $C_c(J\backslash G(F)/J)$
$\DeclareMathOperator\ch{ch}$Let $F$ be a non-archimedean local field, $\mathcal{O}$ its ring of integers, $\mathfrak{p}$ its maximal ideal and $\pi$ a uniformizer. I shall use $\kappa(F)$ to denote ...
10
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Has anyone met this "$q$-character" table for $S_4$?
Is anyone aware of the following $q$-character table for the
symmetric group $S_4$?
\begin{array}{|c|c|c|c|c|c|}
\hline
\mathrm{conj}\backslash\mathrm{rep}
& 2+1+1 & 3+1 & ...
1
vote
1
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169
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Commutative subalgebra of Iwahori-Hecke algebra
I am currently reading the (french) book [1] by Matsumoto. In (2.1.11) the following statement (reformulated in my own words/notation) appears:
Let $(W,S)$ be a Coxeter system, let $R$ be a ...
7
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Naive Schur-Weyl duality for the 0-Hecke algebra
The 0-Hecke algebra $\mathcal{H}_n(0)$ is the $\Bbb{C}$-algbra generated by elements $T_1,
\dots, T_{n-1}$ satisfying the braid relations
and the idempotency relations $T_i^2 = T_i$.
It is known that $...
3
votes
0
answers
66
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LLT polynomials and graded Specht modules
In the paper ``Ribbon Tableaux, Hall-Littlewood Functions, Quantum Affine Algebras And Unipotent Varieties'' Lascoux, Leclerc and Thibon define polynomials which quantise the Schur functions. These $...
3
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133
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Barr's element and the type-A Iwahori–Hecke algebra
Let $\mathfrak{S}_n$ denote the symmetric group on $n$ letters. Barr's element $\mathcal{S}(n) \in \Bbb{R}\bigl[ \mathfrak{S}_n \bigr]$ is defined as
\begin{equation}
\mathcal{S}(n) := \ \sum_{i=1}^{n-...
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Hecke algebras with modified braid relations
I'm studying certain games on graphs on $n$ vertices and it turns out that I get a matrix algebra with generators $T_i , i=1,\dotsc,n$ satisfying a certain type of relations. Here the $T_i$ are ...
4
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On the order of the head of product of two simple modules over Quiver Hecke Algebras
My question is:
We assume the underlying quiver is a Dynkin quiver. Let $L(\lambda)$ and $L(\mu)$ be two simple modules over Quiver Hecke algebra $R$ where $\lambda$ and $\mu$ are two Konstant ...
1
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Block sum for degenerate affine Hecke algebras
The degenerate affine Hecke algebra $H_k$ over a field $F$ is the algebra with generators $s_1,\ldots,s_{k-1}$ and $x_1,\ldots,x_k$, subject to the following relations:
$s_is_js_i=s_js_is_j$ for $i=j\...
3
votes
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answers
89
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compactly induction of smooth modules over Hecke algebras
Let $G$ be a locally profinite group and $H$ its closed subgroup. It is well-known that a smooth representation of $G$ is identified with a smooth module over $\mathcal{H}(G)$, where $\mathcal{H}(G)$ ...
13
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204
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Hidden grading on $kS_n$
Brundan and Kleshchev showed that if $k$ is a field of characteristic $p$, then the group ring $kS_n$ of the symmetric group $S_n$ admits an integer grading which is nontrivial in the sense that it is ...
1
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0
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65
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When is an affine Hecke algebra of type A, a quantum Lie algebra?
An affine Hecke algebra of type $A_{k-1}$ is an unital, universal, associative C-algebra generated by the elements $T_1, \dots, T_{k-1}$, $X_1, \dots , X_k$, $X_1^{-1}, \dots , X_k^{-1}$ subject to ...
10
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3
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Positivity of Iwahori–Hecke algebra characters on the Kazhdan-Lusztig basis
$\DeclareMathOperator\tr{tr}$I'm interested in the irreducible characters of a finite Iwahori–Hecke algebra evaluated at the Kazhdan–Lusztig basis. These are Laurent polynomials.
Are the coefficients ...
6
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Positivity of Schur elements in Iwahori-Hecke algebras
I'm interested in finite Iwahori-Hecke algebras.
If $\mathcal{H}$ is such a Hecke algebra, defined over $\mathbb{Z}[q^{\pm 1/2}]$, and $\Lambda$ an irreductible representation, there is the notion of ...
8
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3
answers
592
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Motivation for the Kazhdan-Lusztig involution
I would like to know about the motivation behind the Kazhdan–Lusztig involution on an Iwahori–Hecke algebra.
I'll borrow the conventions from Libedinsky's Gentle introduction to Soergel bimodules I: ...
7
votes
2
answers
855
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Reference of J.L. Waldspurger's paper on Shimura correspondence
I want to find reference of Waldspurger's paper referred at "Sur les coefficients de Fourier des formes modulaires de poids demi-entier" J. Math. Pures Appl. (9) 60 (1981), no. 4, 375–484 (...
4
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Relationship between Hecke algebra and center of universal enveloping algebra (and the Harish-Chandra isomorphism)
Let $G$ be a semisimple Lie group of noncompact type and let $K$ be a maximal compact subgroup. Let $\mathfrak{g} = \mathfrak{p} \oplus \mathfrak{k}$ be the Cartan decomposition coming from some ...
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0
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50
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Promoting representation of a subgroup to representation of an action groupoid
Suppose I have a group $G$, a subgroup $K \leq G$, and a representation $(\sigma, V)$ of $K$.
There is a natural left action of $G$ on $X := G/K \times G/K$ given by $g \cdot (g'K,g''K) = (gg'K,gg''K)$...
4
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Kazhdan-Lusztig basis elements appearing in product with distinguished involution
My apologies if the below is too malformed to make sense.
Let $(W,S)$ be the affine Weyl group of a reductive group $G$, and let $\{C_w\}$ be the Kazhdan-Lusztig $C$-basis (an answer in terms of the $...
8
votes
1
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Structure constants for the double coset algebra of a Young subgroup
Fix a Young subgroup $H_\lambda \subseteq \mathcal S_n$, where $\lambda \vdash n$ is a partition of $n$ with $k$ blocks. Inside the group algebra $\mathbb C[\mathcal S_n]$, consider the idempotent
$$\...
8
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1
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Hecke algebra relation versus $\operatorname{SL}_2$ trace relation
The quadratic relation in the (type $A$) Hecke algebra is $(T-t)(T+t^{-1}) =0$, which can be rewritten as
$$
T-T^{-1} = t-t^{-1}$$
Suppose $A \in \operatorname{SL}_2(\mathbb{Q})$ with eigenvalues $a,...
1
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1
answer
218
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Algebra of Hecke operators on $M_k(\mathrm{SL}_2\mathbb{Z})$ is an integral domain?
Let $M_k(\mathrm{SL}_2\mathbb{Z})$ be the space of modular forms of (integer) weight for the full modular group. Let $\mathbf{H}$ denote the Algebra generated by the Hecke operators $T_n$. Is $\mathbf{...
3
votes
0
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141
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Classical Hecke operators and Hecke algebra of type $A_1$
What's the relation between the classical Hecke operators (as defined in J. P. Serre's A course in arithmetic chapter 6) and the Hecke algebra of type $A_1$, i.e. the algebra generated by the vertices ...
3
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1
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Reference request: Finite (multi-parameter) Iwahori-Hecke algebras are pairwise isomorphic
Let $(W,S)$ be a Coxeter system. Let $q=(q_s)_{s\in S} \in \mathbb{R}^{\text{#}S}$ be a tuple of positive real numbers with $q_s=q_t$ whenever $s$ and $t$ are conjugate to each other. Follwing Davis', ...
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On the status of some conjectures mentioned/used in Harish Chandra's 1970 lecture notes
In van Dijk's notes of Harish Chandra's lectures on harmonic analysis, several conjectures are mentioned throughout, such as in Part 1, section 4 of van Dijk's notes
Conjecture I : Let $\omega$ be ...
6
votes
1
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447
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Cusp forms have an orthonormal basis of eigenfunctions for all Hecke operators
I am reading Langlands' pape Euler Products and have a few questions. Let $G$ be a split adjoint semisimple group over $\mathbb Q$. If $p$ is a place of $\mathbb Q$, finite or infinite, let $G_{\...
13
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1
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How does one compute the Hecke algebra acting on modular forms?
I asked this on mathstackexchange, but got no answer.
Let $N\geq1$ be an integer, and let $\mathbb{T}$ be the Hecke algebra acting on the cusp forms of weight k and level $\Gamma_0(N)$.
Then $\...
4
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0
answers
134
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Homogenous Hermitian form on the KLR algebra
Does there exist a homogenous conjugate-linear automorphism of the KLR algebra? I want to be able to define a homogenous Hermitian form on the (Specht) modules of the (cyclotomic) KLR algebra.
3
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0
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87
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Flag variety over quaternions and its Hecke algebra
Consider cell decomposition of flag variety of $\mathbb{H}^{n}$ into orbits under the action of $B(\mathbb{H})$ - group of upper triangular matrices with coefficients in $\mathbb{H}$. I think cells ...
4
votes
1
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321
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Volumes of double cosets $KtK$
Let $G$ be the group of rational points of a connected reductive group $\mathbb G$ defined over a non-archimedean local field $F$. For simplicity sake, I assume that $\mathbb G$ is split over $F$. Let ...
7
votes
1
answer
495
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Smallest Mazur's good prime
Let $p$ and $\ell$ be primes $\geq 5$ such that $\ell$ divides $p-1$. Following Mazur, we say that a prime $q$ is a $\textit{good prime}$ if $\ell$ does not divide $q-1$ and $q$ is not a $\ell$th ...
2
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0
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55
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Admissible (unitary) spherical representation $sl(2,Q_p)$. Does dimension fixed point vector increase proportional index
I am using terminology of Cartier's Harmonic analysis on trees. Take $\pi$ be one of the irreducible principal or complementary (unitary) spehrical series of $Sl(2, Q_p)$. Let $K$ be the maximal ...
5
votes
2
answers
491
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Basic theorem on induction for representations of $p$-adic groups
I know a lot of places where the following is sparsely proved, but I remember there was some paper where I read it in basically the same form I write it, but unfortunately I can't remember where it ...
1
vote
0
answers
38
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Decomposition numbers of characteristic 0 Ariki-Koike algebras for q=0 or q generic
Consider a complex Ariki-Koike algebra $H:=H(q;Q_1,\dots, Q_\ell)$ for some invertible elements $q, Q_1,
\dots, Q_\ell$ of $\mathbb{C}$, i.e. an associative $\mathbb{C}$-algebra with generators $T_0, \...
2
votes
0
answers
53
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Branching rule for degenerate cyclotomic Hecke algebras
Grojnowski and Vazirani showed that there is a crystal isomorphism between the crystal defined by modular branching of simple modules of Ariki-Koike algebras and that of an integral highest weight ...
4
votes
1
answer
280
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Hecke algebra $\mathcal H(\operatorname{GL}_2(\mathbb Q_p)/\operatorname{GL}_2(\mathbb Z_p))$ and Hecke operators
I was reading James Cogdell's notes here on automorphic representations and came to the following claim about the spherical Hecke algebra $\mathcal H(\operatorname{GL}_2(\mathbb Q_p), \operatorname{GL}...
3
votes
1
answer
203
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Basis for Annular Skein Algebra
Background/Notation:
Given the Iwahori-Hecke algebra $H_{n}$ (over some ring commutative ring $R$ with identity) with generators $\{T_{1},\ldots T_{n-1}\}$, we know it has basis
$\{T_{w}\}_{w\in S_{...
4
votes
1
answer
331
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Examples of non-trivial Kazhdan-Lusztig polynomials
I'm looking for examples of non-trivial Kazhdan-Lusztig polynomials, specifically in the case where the Coxeter system is a Weyl group.
For example, the simplest polynomial with non-trivial $q$-...