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We investigate the algebro-geometric structure of a novel two-parameter quantum deformation which exhibits the nature of a semidirect or cross-product algebra built upon GL(2) x GL(1), and is related to several other known examples of…

Quantum Algebra · Mathematics 2007-05-23 Deepak Parashar

We develop a complete theory of non-formal deformation quantization on the cotangent bundle of a weakly exponential Lie group. An appropriate integral formula for the star-product is introduced together with a suitable space of functions on…

Mathematical Physics · Physics 2024-05-29 Ziemowit Domański

We consider a family of dynamical systems (A,alpha,L) in which alpha is an endomorphism of a C*-algebra A and L is a transfer operator for \alpha. We extend Exel's construction of a crossed product to cover non-unital algebras A, and show…

Operator Algebras · Mathematics 2015-05-13 Nathan Brownlowe , Iain Raeburn , Sean T. Vittadello

The recently developed theory of partial actions of discrete groups on $C^*$-algebras is extended. A related concept of actions of inverse semigroups on $C^*$-algebras is defined, including covariant representations and crossed products.…

funct-an · Mathematics 2008-02-03 Nandor Sieben

We give complete descriptions of the tracial states on both the universal and reduced crossed products of a C*-dynamical system consisting of a unital C*-algebra and a discrete group. In particular, we also answer the question of when the…

Operator Algebras · Mathematics 2021-08-19 Dan Ursu

This dissertation is an exposition of Kontsevich's proof of the formality theorem and the classification of deformation quantisation on a Poisson manifold. We begin with an account of the physical background and introduce the Weyl-Moyal…

Mathematical Physics · Physics 2022-07-19 Peize Liu

In this paper we study deformations of $C^*$-algebras that are given as cross-sectional $C^*$-algebras of Fell bundles over locally compact groups $G$. Our deformation comes from a direct deformation of the Fell bundles via certain…

Operator Algebras · Mathematics 2026-01-14 Alcides Buss , Siegfried Echterhoff

Let $\mathbb B$ be a Lie group admitting a left-invariant negatively curved K\"ahlerian structure. Consider a strongly continuous action $\alpha$ of $\mathbb B$ on a Fr\'echet algebra $\mathcal A$. Denote by $\mathcal A^\infty$ the…

Operator Algebras · Mathematics 2019-06-05 Pierre Bieliavsky , Victor Gayral

Let X be a smooth affine algebraic variety over a field K of characteristic 0, and let R be a complete parameter K-algebra (e.g. R = K[[h]]). We consider associative (resp. Poisson) R-deformations of the structure sheaf O_X. The set of…

Algebraic Geometry · Mathematics 2012-09-28 Amnon Yekutieli

We compute the Hochschild homology of the crossed product $\Bbb C[S_n]\ltimes A^{\otimes n}$ in terms of the Hochschild homology of the associative algebra $A$ (over $\Bbb C$). It allows us to compute the Hochschild (co)homology of $\Bbb…

Quantum Algebra · Mathematics 2007-05-23 Pavel Etingof , Alexei Oblomkov

We prove that a number of classes of separable unital C*-algebras are closed under crossed products by finite group actions with the Rokhlin property, including: (1) AI algebras, AT algebras, and related classes characterized by direct…

Operator Algebras · Mathematics 2009-02-06 Hiroyuki Osaka , N. Christopher Phillips

Any deformation of a Weyl or Clifford algebra A can be realized through a `deforming map', i.e. a formal change of generators in A. This is true in particular if A is covariant under a Lie algebra g and its deformation is induced by some…

q-alg · Mathematics 2009-10-30 Gaetano Fiore

Given a C*-dynamical system (A,G,\alpha), we say that A is a weakly proper (X\rtimes G)-algebra if there exists a proper G-space X together with a nondegenerate G-equivariant *-homomorphism \phi:C_0(X)->M(A). Weakly proper G-algebras form a…

Operator Algebras · Mathematics 2014-06-02 Alcides Buss , Siegfried Echterhoff

We introduce the notion of a crossed product of an algebra by a coalgebra $C$, which generalises the notion of a crossed product by a bialgebra well-studied in the theory of Hopf algebras. The result of such a crossed product is an algebra…

q-alg · Mathematics 2008-02-03 Tomasz Brzezinski

We define and study an analogue of the Baum-Connes assembly map for complex semisimple quantum groups, that is, Drinfeld doubles of $ q $-deformations of compact semisimple Lie groups. Our starting point is the deformation picture of the…

Operator Algebras · Mathematics 2018-04-26 Andrew Monk , Christian Voigt

We develop a deformation framework for $C^*$-algebras equipped with a coaction of a locally compact quantum group, formulated intrinsically at the level of spectral subspaces determined by the coaction. The construction is defined…

Operator Algebras · Mathematics 2026-01-21 Amandip Sangha

We give a new definition for the crossed-product of a C*-algebra A by a *-endomorphism \alpha, which depends not only on the pair (A,\alpha) but also on the choice of a transfer operator (defined in the paper). With this we generalize some…

Operator Algebras · Mathematics 2007-05-23 Ruy Exel

Deformation theory refers to an apparatus in many parts of math and physics for going from an infinitesimal (= first order) deformation to a full deformation, either formal or convergent appropriately. If the algebra being deformed is that…

High Energy Physics - Theory · Physics 2015-10-28 Andreas Deser

Using duality and topological theory of well behaved Hopf algebras (as defined in [2]) we construct star-product models of non compact quantum groups from Drinfeld and Reshetikhin standard deformations of enveloping Hopf algebras of simple…

High Energy Physics - Theory · Physics 2009-10-28 Frédéric Bidegain , Georges Pinczon

We develop criteria to guarantee uniqueness of the C$^*$-norm on a *-algebra $\mathcal{B}$. Nontrivial examples are provided by the noncommutative algebras of $\mathcal{C}$-valued functions $\mathcal{S}_J^\mathcal{C}(\mathbb{R}^n)$ and…

Operator Algebras · Mathematics 2025-05-16 Rodrigo A. H. M. Cabral , Michael Forger , Severino T. Melo