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2,800
The moment mapping for a unitary representation
math.RT
For any unitary representation of an arbitrary Lie group I construct a moment mapping from the space of smooth vectors of the representation into the dual of the Lie algebra. This moment mapping is equivariant and smooth. For the space of analytic vectors the same construction is possible and leads to a real analytic m...
math
2,801
All unitary representations admit moment mappings
math.RT
This is a review of [Michor, Peter W.: The moment mapping for a unitary representation, Ann. Global Anal. Geometry, 8, No 3(1990), 299--313] including a careful description of calculus in infinite dimensions. For any unitary representation of an arbitrary Lie group I construct a moment mapping from the space of smooth ...
math
2,802
Nilpotent orbits, normality, and Hamiltonian group actions
math.RT
Let $M$ be a $G$-covering of a nilpotent orbit in $\g$ where $G$ is a complex semisimple Lie group and $\g=\text{Lie}(G)$. We prove that under Poisson bracket the space $R[2]$ of homogeneous functions on $M$ of degree 2 is the unique maximal semisimple Lie subalgebra of $R=R(M)$ containing $\g$. The action of $\g'\sime...
math
2,803
Homogeneous functions on light cones: the infinitesimal structure of some degenerate principal series representations
math.RT
In this paper we study the reducibility, composition series and unitarity of the components of some degenerate principal series representations of $\RMO(p,q)$, $\RMU(p,q)$ and $\SP(p,q)$. This is done by realizing these representations in paces of homogeneous functions on light cones and writing down the explicit actio...
math
2,804
An external approach to unitary representations
math.RT
The main aim of this paper is to present the ideas which lead first to the solution of the unitarizability problem for $\GL(n)$ over nonarchimedean local fields and to the recognition that the same result holds over archimedean local fields, a result which was proved by Vogan using an internal approach. Let us say that...
math
2,805
On the convergence of the zeta function for certain prehomogeneous vector spaces
math.RT
Let (G,V) be an irreducible prehomogeneous vector space defined over a number field k, P in k[V] a relative invariant polynomial, and X a rational character of G such that P(gx)=X(g)P(x). Let V_k^{ss}={x \in V_k such that P(x) is not equal to 0}. For x in V_k^{ss}, let G_x be the stabilizer of x, and G_x^0 the connecte...
math
2,806
The moment map for a multiplicity free action
math.RT
Let $K$ be a compact connected Lie group acting unitarily on a finite-dimensional complex vector space $V$. One calls this a {\em multiplicity-free} action whenever the $K$-isotypic components of $\C[V]$ are $K$-irreducible. We have shown that this is the case if and only if the moment map $\tau:V\rightarrow\k^*$ for t...
math
2,807
Exceptional Theta-correspondences I
math.RT
Let $G$ be a split simply laced group defined over a $p$-adic field $F$. In this paper we study the restriction of the minimal representation of $G$ to various dual pairs in $G$. For example, the restriction of the minimal representation of $E_7$ to the dual pair $G_2 \times{}$Sp(6) gives the non-endoscopic Langlands l...
math
2,808
Inversion of an integral transform and ladder representations of U(1,q)
math.RT
An integral transform for G=U(1,q) is studied. The transform maps the positive spin ladder representations of G on a Bargmann-Segal-Fock space F_n^1,q into a space of polynomial-valued functions on the bounded realization B^q of G/K. An inversion is given for the transform and unitary structures are given for the geome...
math
2,809
On the automorphism groups of complex homogeneous spaces
math.RT
If G is a (connected) complex Lie Group and Z is a generalized flag manifold for G, the the open orbits D of a (connected) real form G_0 of G form an interesting class of complex homogeneous spaces, which play an important role in the representation theory of G_0. We find that the group of automorphisms, i.e., the holo...
math
2,810
On the Shintani zeta function for the space of binary tri-Hermitian forms
math.RT
In this paper, we consider the most non-split parabolic D_4 type prehomogeneous vector space. The vector space is an analogue of the space of Hermitian forms. We determine the principal part of the zeta function.
math
2,811
On Shintani zeta functions for GL(2)
math.RT
In this paper we consider an analogue of the zeta function for not necessarily prehomogeneous representations of GL(2) and compute some of the poles.
math
2,812
Harmonic Analysis on the Finite Twisted Poincaré Upper Half Plane
math.RT
We prove that the induced representation from a non trivial character of the Coxeter torus of GL$(2,F)$, for a finite field $F$, is multiplicity-free; we give an explicit description of the corresponding (twisted) spherical functions and a version of the Heisenberg Uncertainty Principle.
math
2,813
Classification of $N$-(super)-extended Poincaré algebras and bilinear invariants of the spinor representation of $Spin(p,q)$
math.RT
We classify extended Poincar\'e Lie super algebras and Lie algebras of any signature (p,q), that is Lie super algebras and Z_2-graded Lie algebras g = g_0 + g_1, where g_0 = so(V) + V is the (generalized) Poincar\'e Lie algebra of the pseudo Euclidean vector space V = R^{p,q} of signature (p,q) and g_1 = S is the spino...
math
2,814
Some results on the admissible representations of non-connected reductive p-adic groups
math.RT
We examine the theory of induced representations for non-connected reductive $p$-adic groups for which $G/G^0$ is abelian. We first examine the structure of those representations of the form $\Ind_{P^0}^G(\sigma),$ where $P^0$ is a parabolic subgroup of $G^0$ and $\s$ is a discrete series representation of the Levi com...
math
2,815
Murnaghan-Nakayama rules for characters of Iwahori-Hecke algebras of the complex reflection groups G(r,p,n)
math.RT
Iwahori-Hecke algebras for the infinite series of complex reflection groups $G(r,p,n)$ were constructed recently in the work of Ariki and Koike, Brou\'e and Malle, and Ariki. In this paper we give Murnaghan-Nakayama type formulas for computing the irreducible characters of these algebras. Our method is a generalization...
math
2,816
Seminormal representations of Weyl groups and Iwahori-Hecke algebras
math.RT
The purpose of this paper is to describe a general procedure for computing analogues of Young's seminormal representations of the symmetric groups. The method is to generalize the Jucys-Murphy elements in the group algebras of the symmetric groups to arbitrary Weyl groups and Iwahori-Hecke algebras. The combinatorics o...
math
2,817
On local coefficients for non-generic representations of some classical groups
math.RT
This paper is concerned with representations of split orthogonal and quasi-split unitary groups over a nonarchimedean local field which are not generic, but which support a unique model of a different kind, the generalized Bessel model. The properties of the Bessel models under induction are studied, and an analogue of...
math
2,818
Groupoids: unifying internal and external symmetry
math.RT
The aim of this paper is to explain, mostly through examples, what groupoids are and how they describe symmetry. We will begin with elementary examples, with discrete symmetry, and end with examples in the differentiable setting which involve Lie groupoids and their corresponding infinitesimal objects, Lie algebroids.
math
2,819
Prehomogeneous vector spaces and ergodic theory I
math.RT
This is part one of a series of papers. In this series of papers, we consider problems analogous to the Oppenheim conjecture from the viewpoint of prehomogeneous vector spaces.
math
2,820
Prehomogeneous vector spaces, Eisenstein series, and invariant theory
math.RT
In this paper, we give an introduction to the rationality of the equivariant Morse stratification, and state the author's results on zeta functions of prehomogeneous vector spaces.
math
2,821
Prehomogeneous vector spaces and ergodic theory II
math.RT
We apply M. Ratner's theorem on closures of unipotent orbits to the study of three families of prehomogeneous vector spaces. As a result, we prove analogues of the Oppenheim Conjecture for simultaneous approximation by values of certain alternating bilinear forms in an even number of variables and certain alternating t...
math
2,822
Correction to "Measurable quotients of unipotent translations on homogeneous spaces
math.RT
The statements of Main~Theorem~1.1 and Theorem~2.1 of the author's paper [\emph{Trans.\ Amer.\ Math.\ Soc.}\ {\bf 345} (1994) 577--594] should assume that $\Gamma $~is discrete and $G$~is connected. (Cors.~1.3, 5.6, and~5.8 are affected similarly.) These restrictions can be removed if the conclusions of the results are...
math
2,823
Superrigid subgroups of solvable Lie groups
math.RT
Let $\Gamma$ be a discrete subgroup of a simply connected, solvable Lie group~$G$, such that $\Ad_G\Gamma$ has the same Zariski closure as $\Ad G$. If $\alpha \colon \Gamma \to \GL_n(\real)$ is any finite-dimensional representation of~$\Gamma $,we show that $\alpha$ virtually extends to a continuous representation~$\si...
math
2,824
Correction to "Zero-entropy affine maps on homogeneous spaces
math.RT
Proposition~6.4 of the author's paper {\origpaper} is incorrect. This invalid proposition was used in the proof of Corollary~6.5, so we provide a new proof of the latter result.
math
2,825
Cohomology at infinity and the well-rounded retract for general Linear Groups
math.RT
Let $\bold G$ be a reductive algebraic group defined over $\Q$, and let $\Gamma$ be an arithmetic subgroup of $\bold G(\Q)$. Let $X$ be the symmetric space for $\bold G(\R)$, and assume $X$ is contractible. Then the cohomology (mod torsion) of the space $X/\Gamma$ is the same as the cohomology of $\Gamma$. In turn, $X/...
math
2,826
Prehomogeneous vector spaces and field extensions III
math.RT
In this paper, we determine the rational orbit decomposition for two prehomogeneous vector spaces associated with the simple group of type G_2.
math
2,827
Prehomogeneous vector spaces and ergodic theory III
math.RT
Let H_1=SL(5), H_2=SL(3), H=H_1 \times H_2. It is known that (G,V) is a prehomogeneous vector space (see [22], [26], [25], for the definition of prehomogeneous vector spaces). A non-constant polynomial \delta(x) on V is called a relative invariant polynomial if there exists a character \chi such that \delta(gx)=\chi(g)...
math
2,828
A remark on the regularity of prehomogeneous vector spaces
math.RT
In this note, we prove that if $(G,V)$ is a prehomogeneous vector space over any field $k$ such that the stabilizer of a generic point is reductive, the set of semi-stable points is a single orbit over the separable closure of $k$.
math
2,829
Ratner's theorem and invariant theory
math.RT
In this note, we consider applications of Ratner's theorem to constructions of families of polynomials with dense values on the set of primitive integer points from the viewpoint of invariant theory.
math
2,830
Simple Lie algebras which generalize Witt algebras
math.RT
We introduce a new class of simple Lie algebras $W(n,m)$ that generalize the Witt algebra by using "exponential" functions, and also a subalgebra $W^*(n,m)$ thereof; and we show each derivation of $W^*(1,0)$ can be written as a sum of an inner derivation and a scalar derivation. The Lie algebra $W(n,m)$ is $Z$-graded a...
math
2,831
Generalized W-type and H-type algebras
math.RT
It is well known that the Poisson Lie algebra is isomorphic to the Hamiltonian Lie algebra. We show that the Poisson Lie algebra can be embedded properly in the special type Lie algebra. We also generalize the Hamiltonian Lie algebra using exponential functions, and we show that these Lie algebras are simple.
math
2,832
Down-up Algebras
math.RT
The algebra generated by the down and up operators on a differential partially ordered set (poset) encodes essential enumerative and structural properties of the poset. Motivated by the algebras generated by the down and up operators on posets, we introduce here a family of infinite-dimensional associative algebras cal...
math
2,833
Approximate representations and Virasoro algebra
math.RT
In the paper there are investigated various approximate representations of the infinite dimensional $\Bbb Z$--graded Lie algebras: the Witt algebra of all Laurent polynomial vector fields on a circle and its one-dimensional nontrivial central extension, the Virasoro algebra, by the infinite dimensional hidden symmetrie...
math
2,834
Tensor products of singular representations and an extension of the theta-correspondence
math.RT
In this paper we consider the problem of decomposing tensor products of certain singular unitary representations of a semisimple Lie group G. Using explicit models for these representations (constructed earlier by one of us) we show that the decomposition is controlled by a reductive homogeneous space G'/H'. Our proced...
math
2,835
Generalized Spencer Cohomology and filtered Deformations of Z-graded Lie Superalgebras
math.RT
In this paper we introduce generalized Spencer cohomology for finite depth Z-graded Lie (super)algebras. We develop a method of finding filtered deformations of such Z-graded Lie (super)algebras based on this cohomology. As an application we determine all simple filtered deformations of certain Z-graded Lie superalgebr...
math
2,836
The generalized Witt algebras using additive maps
math.RT
Wawamoto generalized the Witt algebra using Laurent extension of polynomial ring. We construct the generalized Witt algebra $W(g_p,n)$ by using an additive map $g_p$ from a set of integers into a field of characteristic zero where $1\leq p \leq n.$
math
2,837
Cross-projective representations of pairs of anticommutative algebras, alloys and finite-dimensional irreducible representations of some infinite-dimensional Lie algebras
math.RT
The article is devoted to some ``strange'' phenomena of representation theory and their interrelations. Cross-projective representations of pairs of anticommutative algebras, alloys, their universal envelopping Lie algebras and their representations, quaternary algebras and their alloyability are discussed. Considered ...
math
2,838
Weight modules of direct limit Lie algebras
math.RT
In this article we initiate a systematic study of irreducible weight modules over direct limits of reductive Lie algebras, and in particular over the simple Lie algebras $A(\infty)$, $B(\infty)$, $C(\infty)$ and $D(\infty)$. Our main tool is the shadow method introduced recently in \cite{DMP}. The integrable irreducibl...
math
2,839
The Fine Structure of Translation Functors
math.RT
Let E be a simple finite dimensional representation of a semisimple Lie algebra with extremal weight nu and choose nonzero e in E_{nu}. Let M(tau) be the Verma module with highest weight tau and v_{tau} in M(tau)_{tau} its canonical generator. We investigate the projection of e \otimes v_{tau} in E \otimes M(tau) on th...
math
2,840
Gröbner-Shirshov Bases for Lie Superalgebras and Their Universal Enveloping Algebras
math.RT
We show that a set of monic polynomials in the free Lie superalgebra is a Gr\"obner-Shirshov basis for a Lie superalgebra if and only if it is a Gr\"obner-Shirshov basis for its universal enveloping algebra. We investigate the structure of Gr\"obner-Shirshov bases for Kac-Moody superalgebras and give explicit construct...
math
2,841
Graded Lie Superalgebras, Supertrace Formula, and Orbit Lie Superalgebras
math.RT
Let $\Gamma$ be a countable abelian semigroup and $A$ be a countable abelian group satisfying a certain finiteness condition. Suppose that a group $G$ acts on a $(\Gamma \times A)$-graded Lie superalgebra ${\frak L}=\bigoplus_{(\alpha,a) \in \Gamma\times A} {\frak L}_{(\alpha,a)}$ by Lie superalgebra automorphisms pres...
math
2,842
The Polynomial Behavior of Weight Multiplicities for the Affine Kac-Moody Algebras $A^{(1)}_r$
math.RT
We prove that the multiplicity of an arbitrary dominant weight for an integrable highest weight representation of the affine Kac-Moody algebra $A_{r}^{(1)}$ is a polynomial in the rank $r$. In the process we show that the degree of this polynomial is less than or equal to the depth of the weight with respect to the hig...
math
2,843
Discrete Series for Loop Groups.I. An algebraic Realization of Standard Modules
math.RT
In this paper we consider the category $C (\tilde k, \tilde H)$ of the $(\tilde k, \tilde H)$-modules, including all the Verma modules, where $k$ is some compact Lie algebra and H some Cartan subgroup, $\tilde k$ and $\tilde H$ are the corresponding affine Lie algebra and the affine Cartan group, respectively. To this ...
math
2,844
Irreducible representations of solvable Lie superalgebras
math.RT
The description of irreducible finite dimensional representations of finite dimensional solvable Lie superalgebras over complex numbers given by V.~Kac is refined. In reality these representations are not just induced from a polarization but twisted, as infinite dimensional representations of solvable Lie algebras. Var...
math
2,845
Orthogonal polynomials and Lie superalgebras
math.RT
For the orthogonal Lie algebra O(2n+1), in addition to the conventional set of orthogonal polynomials, another set is produced with the help of the Lie superalgebra OSP(1|2n). Difficulties related with expression of Dyson's constant for the Lie superalgebras are discussed.
math
2,846
The Howe duality and the Projective Representations of Symmetric Groups
math.RT
The symmetric group S_n possesses a nontrivial central extension, whose irreducible representations, different from the irreducible representations of S_n itself, coincide with the irreducible representations of a certain algebra A_n. Recently M.~Nazarov realized irreducible representations of A_n and Young symmetrizer...
math
2,847
On a new class of the commutative subalgebras of the maximal Gel'fand-Kirillov dimension in the universal enveloping algebra of a simple Lie algebra
math.RT
New commutative subalgebras of the maximal Gel'fand-Kirillov dimension in the universal enveloping algebras of classical Lie algebras gl(n) and so(n) are constructed. In the case of sp(n) Gel'fand-Tsetlin algebra is extended to a maximally commutative one.
math
2,848
A duality of the twisted group algebra of the symmetric group and a Lie superalgebra
math.RT
Let A_k denote the twisted group algebra of the symmetric group S_k, whose representations correspond to the nonlinear projective representations of S_k. We establish a duality relation between A_k and a Lie superalgebra q(n), sometimes called the ``queer'' Lie superalgebra. This duality clarifies Schur's formula, in t...
math
2,849
On the classification of unitary representations of reductive Lie groups
math.RT
Suppose G is a real reductive Lie group in Harish-Chandra's class. We propose here a structure for the set \Pi_u(G) of equivalence classes of irreducible unitary representations of G. (The subscript u will be used throughout to indicate structures related to unitary representations.) We decompose \Pi_{u}(G) into disjoi...
math
2,850
A duality of a twisted group algebra of the hyperoctahedral group and the queer Lie superalgebra
math.RT
We establish a duality relation between one of the twisted group algebras of the hyperoctahedral groupf H_k and a Lie superalgebra q(n_0) \oplus q(n_1) for any integers k and n_0, n_1, where q(n_0) and q(n_1) denote the ``queer'' Liesuperalgebras. Note that this twisted group algebra \B'_k belongs to a different cocycl...
math
2,851
Explicit Hilbert spaces for certain unipotent representations II
math.RT
We construct an explicit realization of a minimal representation of G, where G is the conformal group of a real Jordan algebra N. We characterize spherical vectors for these representation and prove that they are closely related to the Bessel K-function $K_\tau (z)$. The resulting construction can be used to study tens...
math
2,852
Raising operators for the Whittaker wave functions of the Toda chain and intertwining operators
math.RT
Intertwiners between representations of Lie groups can be used to obtain relations for matrix elements. We apply this technique to obtain different identities for the wave functions of the open Toda chain, in particular raising operators and bilinear relations for the wave functions at different energy levels. We also ...
math
2,853
Classification of finite dimensional modules of singly atypical type over the Lie superalgebras sl(m/n)
math.RT
We classify the finite dimensional indecomposable sl(m/n)-modules with at least a typical or singly atypical primitive weight. We do this classification not only for weight modules, but also for generalized weight modules. We obtain that such a generalized weight module is simply a module obtained by ``linking'' sub-qu...
math
2,854
NilCoxeter algebras categorify the Weyl algebra
math.RT
We show that induction and restriction functors for inclusions of nilCoxeter algebras provide a categorical realization of the algebra of polynomial differential operators in one variable.
math
2,855
Affine sl_p controls the representation theory of the symmetric group and related Hecke algebras
math.RT
In this paper we prove theorems that describe how the representation theory of the affine Hecke algebra of type A and of related algebras such as the group algebra of the symmetric group are controlled by integrable highest weight representations of the characteristic zero affine Lie algebra \hat{sl}_l. In particular w...
math
2,856
Dimension of a minimal nilpotent orbit
math.RT
We show that the dimension of the minimal nilpotent coadjoint orbit for a complex simple Lie algebra is equal to twice the dual Coxeter number minus two.
math
2,857
Analytic continuation of representations and estimates of automorphic forms
math.RT
Properties of analytic vectors in representations of SL(2,R) are used to give new bounds for the triple products recently considered by P. Sarnak. A conjecture of Sarnak about such products is proved. The results of this paper generalize results of A. Good and M. Jutila about special cases, but the techniques are entir...
math
2,858
Steinberg modules and Donkin pairs
math.RT
We prove that in positive characteristic a module with good filtration for a group of type E6 restricts to a module with good filtration for a subgroup of type F4. (Recall that a filtration of a module for a semisimple algebraic group is called good if its layers are dual Weyl modules.) Our result confirms a conjecture...
math
2,859
Reciprocity Theorems for Holomorphic Representations of Some Infinite-Dimensional Groups
math.RT
In this article we prove several reciprocity theorems for some infinite-dimensional dual pairs of representations on Bargmann-Segal-Fock spaces.
math
2,860
Weyl's character formula for non-connected Lie groups and orbital theory for twisted affine Lie algebras
math.RT
We generalize I. Frenkel's orbital theory for non twisted affine Lie algebras to the case of twisted affine Lie algebras using a character formula for certain non-connected compact Lie groups.
math
2,861
Localization of elementary systems in the theory of Wigner
math.RT
Starting from Wigner's theory of elementary systems and following a recent approach of Schroer we define certain subspaces of localized wave functions in the underlying Hilbert space with the help of the theory of modular von-Neumann algebras of Tomita and Takesaki. We characterize the elements of these subspaces as bo...
math
2,862
Generalized Loop Groups of Complex Manifolds, Gaussian Quasi-Invariant Measures on them and their Representations
math.RT
Loop groups G as families of mappings of the complex manifold M into another complex manifold N preserving marked points $s_0\in M$ and $y_0\in N$ are investigated. Quasi-invariant measures $\mu $ on G relative to dense subgroups $G'$ are constructed. These measures are used for the studying of irreducible representati...
math
2,863
Poisson measures for topological groups and their representations
math.RT
Gaussian quasi-invariant measures on groups of diffeomorphisms and loop groups G relative to dense subgroups G' were constructed. In the non-Archimedean case the wider class of measures was investigated, than in the real case. The cases of Riemann and non-Archimedean manifolds were considered. This article is related w...
math
2,864
On the Ghost Centre of Lie Superalgebras
math.RT
We define a notion of ghost centre of a Lie superalgebra g=g_0+g_1 which is a sum of invariants with respect to the usual adjoint action (centre) and invariants with respect to a twisted adjoint action (``anticentre''). We calculate the anticentre in the case when the top external degree of g_1 is a trivial g_0-module....
math
2,865
On extensions of representations for compact Lie groups
math.RT
Let $H$ be a closed normal subgroup of a compact Lie group $G$ such that $G/H$ is connected. This paper provides a necessary and sufficient condition for every complex representation of $H$ to be extendible to $G$, and also for every complex $G$-vector bundle over the homogeneous space $G/H$ to be trivial. In particula...
math
2,866
Introduction to the Alexandru Conjecture
math.RT
Is a Verma module transformed into another Verma module by a selfequivalence? The answer is affirmative and the proof suggests a notion of standard object in the category of Harish-Chandra modules that coincides often, but not always, with the usual one.
math
2,867
Statement of the Alexandru Conjecture
math.RT
The Vogan Conjectures (sometimes called Kazhdan-Lusztig Conjectures) say that a certain algorithm works both on the category of BGG modules and on the category of Harish-Chandra modules. The Alexandru Conjecture tries to uncover the general property common to these two categories which makes Vogan's algorithm work.
math
2,868
A two-box-shift morphism between Specht modules
math.RT
Let n geq 1, let lambda be a partition of n, let mu be a partition arising from lambda by a downwards shift of two boxes situated at the bottom of a column. We give a formula for a ZS_n-linear morphism of order m between the corresponding Specht modules over Z/(m), where m is the box shift length (divided by two in cer...
math
2,869
A simple question about a complicated object
math.RT
Let n and k be positive integers with and k < n. Then of course SU(k,1) is contained into SU(n,1). Moreover, which is less clear - but proved by Khoroshkin -, the representation theory of SU(k,1) at the generalized infinitesimal character of the trivial module can be fully (and even Ext-fully) embedded into that of...
math
2,870
Branching rules for modular fundamental representations of symplectic groups
math.RT
In this paper branching rules for the fundamental representations of the symplectic groups in positive characteristic are found. The submodule structure of the restrictions of the fundamental modules for the group $Sp_{2n}(K)$ to the naturally embedded subgroup $Sp_{2n-2}(K)$ is determined. As a corollary, inductive sy...
math
2,871
On an asymptotic behavior of elements of order p in irreducible representations of the classical algebraic groups with large enough highest weights
math.RT
The behavior of the images of a fixed element of order p in irreducible representations of a classical algebraic group in odd characteristic p with highest weights large enough with respect to p and this element is investigated. Lower estimates for the number of Jordan blocks of size p in images of such elements that l...
math
2,872
Normalisation des opérateurs d'entrelacement et réductibilité des induites de cuspidales; le cas des groupes classiques p-adiques
math.RT
On montre comment les conjectures d'Arthur permettent de calculer les points de r\'eductibilit\'e pour les induites de cuspidales des groupes classiques. Les conjectures d'Arthur utilis\'ees portent sur l'existence d'un rel\`evement faible des repr\'esentations automorphes cuspidales d'un groupe classique vers un group...
math
2,873
Discrete group actions on Stein domains in complex Lie groups
math.RT
This paper deals with the analytic continuation of holomorphic automorphic forms on a Lie group $G$. We prove that for any discrete subgroup $\Gamma$ of $G$ there always exists a non-trivial holomorphic automorphic form, i.e., there exists a $\Gamma$-spherical unitary highest weight representation of $G$. Holomorphic a...
math
2,874
Formal dimension for semisimple symmetric spaces
math.RT
In this paper we generalize Harish Chandra's formula for the formal dimension of a representation of the holomorphic discrete series of a hermitian Lie group $G$ to semisimple symmetric spaces $G/H$.
math
2,875
The c-function for non-compactly causal symmetric spaces
math.RT
In this paper we prove the product formula for the c-function of non-compactly causal symmetric spaces.
math
2,876
Grothendieck groups and tilting objects
math.RT
Let C be a connected noetherian hereditary abelian Ext-finite category with Serre functor over an algebraically closed field k, with finite dimensional homomorphism and extension spaces. Using the classification of such categories from math.RT/9911242, we prove that if C has some object of infinite length, then the Gro...
math
2,877
Affine Lie Algebras and Tame Quivers
math.RT
C.M. Ringel defined Hall algebra associated with the category of representations of a quiver of Dynkin type and gave an explicit description of the structure constants of the corresponding Lie algebra. We utilize functorial properties of the Hall algebra to give a simple proof of Ringel's result, and to generalize it t...
math
2,878
Characteristic cycles and wave front cycles of representations of reductive Lie groups
math.RT
Vogan and Barbasch-Vogan attach two similar invariants to representations of a reductive Lie group, one by an algebraic process, the other analytic. They conjectured that the two invariants determine each other in a definite manner. Here we prove the conjecture. Our arguments involve two finer invariants -- the charact...
math
2,879
The second cohomology of small irreducible modules for simple algebraic groups
math.RT
Let G be a simple, simply connected and connected algebraic group over an algebraically closed field of characteristic p>0, and let V be a rational G-module such that dim V <= p. According to a result of Jantzen, V is completely reducible, and H^1(G,V)=0. In this paper we show that H^2(G,V) = 0 unless some composition ...
math
2,880
Abelian Unipotent Subgroups of Reductive Groups
math.RT
Let G be a connected reductive group defined over an algebraically closed field k of characteristic p > 0. The purpose of this paper is two-fold. First, when p is a good prime, we give a new proof of the ``order formula'' of D. Testerman for unipotent elements in G; moreover, we show that the same formula determines th...
math
2,881
Rigidity, unitary representations of semisimple groups, and fundamental groups of manifolds with rank one transformation group
math.RT
The article establishes a long list of rigidity properties of lattices in G = SO(n,1) with n>=3 and G = SU(n,1) with n>=2 that are analogous to superrigidity of lattices in higher-rank Lie groups. The arguments are set in the context of strongly L^p unitary representations of G.
math
2,882
Howe Duality for Lie Superalgebras
math.RT
We study a dual pair of general linear Lie superalgebras in the sense of R. Howe. We give an explicit multiplicity-free decomposition of a symmetric and skew-symmetric algebra (in the super sense) under the action of the dual pair and present explicit formulas for the highest weight vectors in each isotypic subspace of...
math
2,883
Invariant differential operators on nonreductive homogeneous spaces
math.RT
A systematic exposition is given of the theory of invariant differential operators on a not necessarily reductive homogeneous space. This exposition is modelled on Helgason's treatment of the general reductive case and the special non-reductive case of the space of horocycles. As a final application the differential op...
math
2,884
Higher orbital integrals, Shalika germs, and the Hochschild homology of Hecke algebras
math.RT
We give a detailed calculation of the Hochschild and cyclic homology of the algebra $\CIc(G)$ of locally constant, compactly supported functions on a reductive p-adic group G. We use these calculations to extend to arbitrary elements the definition the higher orbital integrals introduced in \cite{Blanc-Brylinski} for r...
math
2,885
Projectivity of modules for infinitesimal unipotent group schemes
math.RT
In this paper, it is shown that the projectivity of a rational module for an infinitesimal unipotent group scheme over an algebraically closed field of positive characteristic can be detected on a family of closed subgroups.
math
2,886
Cohomology and projectivity of modules for finite group schemes
math.RT
Let G be a finite group scheme over an algebraically closed field of positive characteristic. Assume further that the connected component of G is unipotent. It is shown that the projectivity of a rational G-module can be detected on a family of closed subgroups. It is further shown that nilpotent cohomology or extensio...
math
2,887
Blocks of Lie Superalgebras of Type W(n)
math.RT
We calculate the blocks of the category of finite-dimensional representations of W(0,n), with n > 2, and show that all are of wild type. As an application, we show that the centre of the universal enveloping algebra is trivial.
math
2,888
Strongly typical representations of the basic classical Lie superalgebras
math.RT
The category of representations with a strongly typical central character of a basic classical Lie superalgebra is proven to be equivalent to the category of representations of its even part corresponding to an appropriate central character. For a Lie superalgebra $osp(1,2l)$ the category of representations with a "g...
math
2,889
Méthode des orbites et formules du caractère pour les représentations tempérées d'un groupe algébrique réel réductif non connexe
math.RT
Let G be a non-connected reductive real Lie group. In this paper, I parametrize the set of irreductible tempered characters of G. Afterwards, I describe these characters by means of some ``Kirillov's formulas'', using the descent method near each elliptic element in G. If G is linear and connected, the parameters tha...
math
2,890
Degenerations of Schubert varieties of SL(n)/B to toric varities
math.RT
Using polytopes defined in an earlier paper, we show in this paper the existence of degenerations of a large class of Schubert varieties of SL_n to toric varieties by extending the method used by Gonciulea and Lakshmibai for a minuscule G/P to Schubert varieties in SL_n
math
2,891
Toric degenerations of Schubert varieties
math.RT
Let $G$ be a simply connected semi-simple complex algebraic group. Fix a maximal torus $T$ and a Borel subgroup $B$ such that $T\subset B\subset G$. Let $W$ the Weyl group of $G$ relative to $T$. For any $w$ in $W$, let $X_w=\bar {BwB/B}$ denote the Schubert variety corresponding to $w$. This talk is concerned with the...
math
2,892
A generating function for the trace of the Iwahori-Hecke algebra
math.RT
The Iwahori-Hecke algebra has a ``natural'' trace $\tau$. This trace is the evaluation at the identity element in the usual interpretation of the Iwahori-Hecke algebra as a sub-algebra of the convolution algebra of a p-adic semi-simple group. The Iwahori-Hecke algebra contains an important commutative sub-algebra ${\bf...
math
2,893
On the spectral decomposition of affine Hecke algebras
math.RT
An affine Hecke algebra H contains a large abelian subalgebra A. The center Z of H is the subalgebra of Weyl group invariant elements in A. The natural trace of the affine Hecke algebra can be written as an integral of a rational $n$ form (with values in the linear dual of H) over a certain cycle in the algebraic torus...
math
2,894
On certain representations of automorphism groups of an algebraically closed field
math.RT
Let k be an algebraically closed field of characteristic zero, F its algebraically closed extension, and G be the group of k-automorphisms of F endowed with a natural topology. One of the purposes of this paper is to show that any non-faithful continuous representation of G factors through a discrete quotient of G. P...
math
2,895
Centralizers of distinguished nilpotent pairs and related problems
math.RT
In this paper, by establishing an explicit and combinatorial description of the centralizer of a distinguished nilpotent pair in a classical simple Lie algebra, we solve in the classical case Panyushev's Conjecture which says that distinguished nilpotent pairs are wonderful, and the classification problem on almost pri...
math
2,896
Some New Applications of Weyl's Multipolarization Operators
math.RT
In Weyl's "The Classical Groups", he introduces some some remarkable differential operators, which he calls "quasi-compositions" of the polarization operators Dij. In the present paper, an equivalent combinatorial formulation is obtained for these operators, and is then used to obtain explicit formulas for the differen...
math
2,897
On tensor categories attached to cells in affine Weyl groups II
math.RT
George Lusztig conjectured that asymptotic affine Hecke algebra of a simply connected group can be explicitly described in terms of convolution algebras. Main Theorem of this note (which is a continuation of RT/0010089) is a weak version of this Conjecture. This version is strong enough to reprove all previously known ...
math
2,898
A generalization of Hall polynomials to ADE case
math.RT
Certain computable polynomials are described whose leading coefficients are equal to multiplicities in the tensor product decomposition for representations of a Lie algebra of ADE type.
math
2,899
Rationality properties of unipotent representations
math.RT
We describe those unipotent representations of a finite group of Lie type which are defined over the rational numbers.
math