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A universal category-theoretical characterization of groupoid equivariant $KK^G$-theory for ${\mathbb{Z}}_2$-graded $C^*$-algebras is established, by observing the ``$KK$-axiom'' that for each $[s,{\cal E} \oplus B, \mathbb{F}] \in…

K-Theory and Homology · Mathematics 2026-04-07 Bernhard Burgstaller

The main purpose of this paper is to investigate conjugate type properties for harmonic $(K,K')$-quasiregular mappings, where $K \geq 1$ and $K' \geq 0$ are constants. We first establish a Riesz type conjugate function theorem for such…

Complex Variables · Mathematics 2025-09-23 Shaolin Chen , David Kalaj

We explicitly construct, in terms of Gelfand--Tsetlin tableaux, a new family of simple positive energy representations for the simple affine vertex algebra V_k(sl_{n+1}) in the minimal nilpotent orbit of sl_{n+1}. These representations are…

Representation Theory · Mathematics 2021-07-26 Vyacheslav Futorny , Oscar Armando Hernandez Morales , Luis Enrique Ramirez

In this paper we study the operator inequality \phi(X)\leq X and the operator equation \phi(X)= X, where \phi is a w^*-continuous positive (resp. completely positive) linear map on B(H). We show that their solutions are in one-to-one…

Operator Algebras · Mathematics 2007-05-23 Gelu Popescu

We prove a spectral theorem for bimodules in the context of graph C*-algebras. A bimodule over a suitable abelian algebra is determined by its spectrum (i.e., its groupoid partial order) iff it is generated by the Cuntz-Krieger partial…

Operator Algebras · Mathematics 2007-05-23 Alan Hopenwasser , Jurtin R. Peters , Stephen C. Power

We show that, when $A$ is a separable C*-algebra, every countably generated Hilbert $A$-module is projective (with bounded module maps as morphisms). We also study the approximate extensions of bounded module maps. In the case that $A$ is a…

Operator Algebras · Mathematics 2023-01-12 Lawrence G. Brown , Huaxin Lin

We prove some general results on the T-equivariant K-theory K_T(G/P) of the flag variety G/P, where G is a semisimple complex algebraic group, P is a parabolic subgroup and T$ is a maximal torus contained in P. In particular, we make a…

Algebraic Geometry · Mathematics 2008-01-21 William Graham , Shrawan Kumar

Convex sets of completely positive maps and positive semidefinite kernels are considered in the most general context of modules over $C^*$-algebras and a complete charaterization of their extreme points is obtained. As a byproduct, we…

Quantum Physics · Physics 2014-03-05 Juha-Pekka Pellonpää

We show that the convolution algebra $K^G(\mathcal{B} \times \mathcal{B})$ is isomorphic to the Based ring of the lowest two-sided cell of the extended affine Weyl group associated to $G$, where $G$ is a connected reductive algebraic group…

Representation Theory · Mathematics 2015-03-13 Sian Nie

We consider a construction of C*-algebras from continuous piecewise monotone maps on the circle which generalizes the crossed product construction for homeomorphisms and more generally the construction of Renault, Deaconu and…

Operator Algebras · Mathematics 2019-02-20 Thomas L. Schmidt , Klaus Thomsen

Let k be an algebraically closed field of characteristic p=2. Let G=F_4 be simply connected over k and let \sigma:G\to G be an endomorphism such that the fixed point set G(\sigma) is a Ree group. We show, using the methods of…

Group Theory · Mathematics 2013-04-10 David I. Stewart

Let C be an additive subgroup of $\Z_{2k}^n$ for any $k\geq 1$. We define a Gray map $\Phi:\Z_{2k}^n \longrightarrow \Z_2^{kn}$ such that $\Phi(\codi)$ is a binary propelinear code and, hence, a Hamming-compatible group code. Moreover,…

Information Theory · Computer Science 2009-07-31 J. Borges , C. Fernandez-Cordoba , J. Rifa

We develop a fundamental theory of compact quantum group equivariant finite extensions of C*-algebras. In particular we focus on the case of quantum homogeneous spaces and give a Tannaka-Krein type result for equivariant correspondences. As…

Operator Algebras · Mathematics 2023-01-13 Mao Hoshino

We give a Pontryagin-Thom-Szucs type construction for non-positive codimensional singular maps, and obtain results about cobordism and bordism groups of -1 codimensional stable maps with prescribed singular fibers.

Geometric Topology · Mathematics 2008-09-20 Boldizsar Kalmar

Let g be a complex simple Lie algebra and h a Cartan subalgebra. The Clifford algebra C(g) of g admits a Harish-Chandra map. Kostant conjectured (as communicated to Bazlov in about 1997) that the value of this map on a (suitably chosen)…

Representation Theory · Mathematics 2011-11-16 Anthony Joseph

Let $k$ be a field of positive characteristic and $K = k(V)$ a function field of a variety $V$ over $k$ and let ${\mathbf A}_K$ be a ring of ad\'{e}les of $K$ with respect to a cofinite set of the places on $K$ corresponding to the divisors…

Number Theory · Mathematics 2010-12-09 Dragos Ghioca , Thomas Scanlon

We prove, without set theoretic assumptions, that every locally presentable category C endowed with a tractable cofibrantly generated class of cofibrations has a unique minimal (or left induced) Quillen model structure. More generally, for…

Category Theory · Mathematics 2020-11-30 Simon Henry

This paper gives an explicit structure theorem for the symmetric group acting on the symmetric algebra of its natural module. Let $G$ be the symmetric group on $x_1,..., x_n$ and let $d_i$ be the $i^{\text{th}}$ elementary symmetric…

Rings and Algebras · Mathematics 2013-01-08 Robert Mckemey

We investigate the representation of the so-called orthogonally $a$-Jensen mappings acting on $C^*$-modules. More precisely, let $\mathfrak{A}$ be a unital $C^*$-algebra with the unit $1$, let $a \in \mathfrak{A}$ be fixed such that $a,…

Operator Algebras · Mathematics 2018-11-20 Ali Zamani

We explore applications of the celebrated construction of the Milnor connecting homomorphism from the odd to the even K-groups in the context of Hopf--Galois theory. For a finitely generated projective module associated to any piecewise…

K-Theory and Homology · Mathematics 2026-04-30 Francesco D'Andrea , Piotr M. Hajac , Tomasz Maszczyk , Bartosz Zieliński