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Generalizing work by Pinzari and Roberts, we characterize actions of a compact quantum group G on C*-algebras in terms of what we call weak unitary tensor functors from Rep G into categories of C*-correspondences. We discuss the relation of…

Operator Algebras · Mathematics 2013-04-04 Sergey Neshveyev

What is the correct noncommutative generalization of the functor $C_0(X) \mapsto \ell^\infty(X)$ for locally compact Hausdorff $X$ having a countable basis? Making the ansatz $K(\ell^2) \mapsto B(\ell^2)$, we expect that every unital…

Operator Algebras · Mathematics 2016-07-20 Andre Kornell

We prove, among other results, that three standard measures of weak non-compactness coincide in preduals of JBW$^*$-triples. This result is new even for preduals of von Neumann algebras. We further provide a characterization of…

Operator Algebras · Mathematics 2019-11-14 Jan Hamhalter , Ondřej F. K. Kalenda , Antonio M. Peralta , Hermann Pfitzner

Let WAP(A) be the space of all weakly almost periodic functionals on a Banach algebra A. The Banach algebra A for which the natural embedding of A into WAP(A)* is bounded below is called a WAP-algebra. We show that the second dual of a…

Functional Analysis · Mathematics 2015-01-27 Bahram Khodsiani , Ali Rejali

We introduce a cohomological invariant arising from a class in nonabelian cohomology. This invariant generalizes the Dixmier-Douady class and encodes the obstruction to a C*-algebra bundle being the fixed-point algebra of a gauge action. As…

Operator Algebras · Mathematics 2011-11-18 Ezio Vasselli

The K-theoretic analog of Spanier-Whitehead duality for noncommutative C*-algebras is shown to hold for the Ruelle algebras associated to irreducible Smale spaces. This had previously been proved only for shifts of finite type. Implications…

K-Theory and Homology · Mathematics 2017-09-25 Jerome Kaminker , Ian F. Putnam , Michael F. Whittaker

Let $A$ be a Banach algebra and $A^{**}$ be the second dual of it. We define $\tilde{Z}_1(A^{**})$ as a weak topological center of $A^{**}$ with respect to first Arens product and find some relations between it and the topological center of…

Functional Analysis · Mathematics 2010-10-27 Kazem Haghnejad Azar

An abstract characterization of weakly monotone $C^*$-algebras, namely the concrete $C^*$-algebras generated by creators and annihilators acting on the so-called weakly monotone Fock spaces, is given in terms of (quotient of) suitable…

Operator Algebras · Mathematics 2025-01-16 Vitonofrio Crismale , Simone Del Vecchio , Stefano Rossi , Janusz Wysoczański

We investigate some subtle and interesting phenomena in the duality theory of operator spaces and operator algebras. In particular, we give several applications of operator space theory, based on the surprising fact that certain maps are…

Operator Algebras · Mathematics 2007-05-23 David P. Blecher , Bojan Magajna

We investigate the question whether the (I)-envelope of any subset of a dual to a Banach space $X$ may be described as the closed convex hull in a suitable topology. If $X$ contains no copy of $\ell^1$ then the weak topology generated by…

Functional Analysis · Mathematics 2025-06-23 Ondřej F. K. Kalenda , Matias Raja

In the theory of C*-algebras, interesting noncommutative structures arise as deformations of the tensor product. For instance, the rotation algebra may be seen as a scalar twist deformation of the tensor product of the functions on the…

Operator Algebras · Mathematics 2013-03-04 Moritz Weber

Let $\mathcal{T}(\mathcal{N})$ be a nest algebra of operators on Hilbert space and let $\mathcal{L}$ be a weakly closed Lie $\mathcal{T}(\mathcal{N})$-module. We construct explicitly the largest possible weakly closed…

Operator Algebras · Mathematics 2015-12-11 Lina Oliveira , Miguel Santos

Let X be a path connected, compact metric space and let A be a unital separable simple nuclear Z-stable real rank zero C*-algebra. We classify all the unital *-embeddings (up to approximate unitary equivalence) of C(X) into A. Specifically,…

Operator Algebras · Mathematics 2007-09-11 P. W. Ng , Wilhelm Winter

We study C*-algebra endomorphims which are special in a weaker sense w.r.t. the notion introduced by Doplicher and Roberts. We assign to such endomorphisms a geometrical invariant, representing a cohomological obstruction for them to be…

Operator Algebras · Mathematics 2011-11-21 Ezio Vasselli

We explicitly construct the C*-algebras arising in the formalism of Topological T-duality due to Mathai and Rosenberg from string-theoretic data in several key examples. We construct a continuous-trace algebra with an action of ${\mathbb…

High Energy Physics - Theory · Physics 2008-10-30 Peter Bouwknegt , Ashwin S. Pande

Let G be a discrete group and $\Gamma$ an almost normal subgroup. The operation of cosets concatanation extended by linearity gives rise to an operator system that is embeddable in a natural C* algebra. The Hecke algebra naturally embeds as…

Operator Algebras · Mathematics 2011-06-14 Florin Radulescu

We study classes of Banach spaces where the points of weak$^*$-weak continuity for the identity mapping on the dual unit ball form a weak$^*$-dense and weak$^*$-$G_{\delta}$ set. We also discuss how this property behaves in higher duals of…

Functional Analysis · Mathematics 2025-06-11 S. Daptari , V. Montesinos , T. S. S. R. K. Rao

In this paper we study the bicomplex version of weighted Hardy spaces. Further, we describe reproducing kernels for the bicomplex weighted Hardy spaces. In particular, we generalize some results which holds for the classical weighted Hardy…

Functional Analysis · Mathematics 2015-03-03 Romesh Kumar , Kulbir Singh , Heera Saini , Sanjay Kumar

Let $A$ be a Banach algebra and $A^{**}$ be the second dual of it. We define $\tilde{Z}_1(A^{**})$ as a weak topological center of $A^{**}$ with respect to first Arens product and find some relations between it and the topological center of…

Functional Analysis · Mathematics 2010-03-18 Kazem Haghnejad Azar

We define the secondary Hochschild complex for an entwining structure over a commutative $k$-algebra $B$. We show that this complex carries the structure of a weak comp algebra. We obtain two distinct cup product structures for the…

Rings and Algebras · Mathematics 2021-05-18 Mamta Balodi , Abhishek Banerjee , Anita Naolekar