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Related papers: A remark about a theorem of Skandalis

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In this mostly expository note, we revisit the K\"unneth theorem in $K$-theory of nonnuclear C*-algebras. We show that, using examples considered by Skandalis, there are algebras satisfying the K\"unneth theorem for the minimal tensor…

K-Theory and Homology · Mathematics 2013-01-08 Otgonbayar Uuye

We show that the Chern-Connes character from Kasparov's bivariant K-theory to bivariant local cyclic cohomology is not always rationally injective. Counterexamples are provided by the reduced group $C^*$-algebras of word-hyperbolic groups…

K-Theory and Homology · Mathematics 2011-04-13 Michael Puschnigg

It is proved that the K_0-group of a cluster C*-algebra is isomorphic to the corresponding cluster algebra. As a corollary, one gets a shorter proof of the positivity conjecture for cluster algebras. As an example, we consider a cluster…

Operator Algebras · Mathematics 2020-09-07 Igor Nikolaev

It is shown that if $A$ and $B$ are unital separable simple nuclear $\mathcal Z$-stable C$^*$-algebras and there is a unital embedding $A \rightarrow B$ which is invertible on $KK$-theory and traces, then $A \cong B$. In particular, two…

Operator Algebras · Mathematics 2024-09-09 Christopher Schafhauser

Recently, E.\ Kirchberg [K1--2] revived the study of pairs of $C^*$-algebras $A,B$ such that there is only one $C^*$-norm on the algebraic tensor product $A\otimes B$, or equivalently such that $A \otimes_{\rm min}B = A\otimes_{\rm max}B$.…

Functional Analysis · Mathematics 2016-09-06 Gilles Pisier

We give an example of a unital C*-algebra $\mathbf{A}$ with a computable presentation and for which neither $K_0(\mathbf{A})$ nor $K_1(\mathbf{A})$ has a computable presentation.

Operator Algebras · Mathematics 2026-02-18 Christopher J. Eagle , Isaac Goldbring , Timothy H. McNicholl , Russell Miller

The C*-algebra qC is the smallest of the C*-algebras qA introduced by Cuntz in the context of KK-theory. An important property of qC is the natural isomorphism of K0 of D with classes of homomorphism from qC to matrix algebras over D. Our…

Operator Algebras · Mathematics 2008-05-28 Terry A. Loring

The functor Max of Mulvey assigns to each unital C*-algebra A the unital involutive quantale Max A of closed linear subspaces of A, and it has been remarked that it classifies unital C*-algebras up to *-isomorphism. In this paper we provide…

Operator Algebras · Mathematics 2007-05-23 David Kruml , Pedro Resende

In this work we construct a C*-algebra from an injective endomorphisms of some group G, allowing the endomorphism to have infinite cokernel. We generalize results obtained by I. Hirshberg and also by J. Cuntz and A. Vershik. In good cases…

Functional Analysis · Mathematics 2018-03-13 Felipe Vieira

We use the Cayley transform to provide an explicit isomorphism at the level of cycles from van Daele $K$-theory to $KK$-theory for graded $C^*$-algebras with a real structure. Isomorphisms between $KK$-theory and complex or real $K$-theory…

K-Theory and Homology · Mathematics 2020-06-09 Chris Bourne , Johannes Kellendonk , Adam Rennie

We show that a monomial algebra $\Lambda$ over an algebraically closed field $K$ is self-injective if and only if each map $\mathrm{soc}(_{\Lambda}\Lambda)\to \ _{\Lambda}\Lambda$ can be extended to an endomorphism of $_{\Lambda}\Lambda$,…

Rings and Algebras · Mathematics 2023-07-18 Ardeline M. Buhphang , Rishabh Goswami , Amit Kuber

We show that the Strong Novikov Conjecture for the maximal C*-algebra C*(G) of a discrete group G is equivalent to a statement in topological K-theory for which the corresponding statement in algebraic K-theory is always true. We also show…

K-Theory and Homology · Mathematics 2011-10-04 Crichton Ogle

We show that a $C^*$-algebra $A$ is nuclear iff there is a constant $K$ and $\alpha<3$ such that, for any bounded homomorphism $u\colon A \to B(H)$, there is an isomorphism $\xi\colon H\to H$ satisfying $\|\xi^{-1}\|\|\xi\| \le…

Operator Algebras · Mathematics 2007-05-23 Gilles Pisier

K-theory for $ \sigma$-C*-algebras (countable inverse limits of C*-algebras) has been investigated by N. C. Phillips [{\it K-Theory} {\bf 3} (1989), 441--478]. We use his representable K-theory to show that the space of Fredholm modular…

Operator Algebras · Mathematics 2016-12-13 Kamran Sharifi

In this paper we show an example of two differential graded algebras that have the same derivator K-theory but non-isomorphic Waldhausen K-theory. We also prove that Maltsiniotis's comparison and localization conjectures for derivator…

K-Theory and Homology · Mathematics 2011-05-31 Fernando Muro , George Raptis

We show that for each discrete group G, the rational assembly map K_*(BG) \otimes Q \to K_*(C*_{max} G) \otimes \Q is injective on classes dual to the subring generated by cohomology classes of degree at most 2 (identifying rational…

K-Theory and Homology · Mathematics 2008-08-21 Bernhard Hanke , Thomas Schick

Let A and B be $C^*$-algebras, A separable, and B $\sigma$-unital and stable. It is shown that there are natural isomorphisms $E(A,B)=KK(SA,Q(B))=[SA,Q(B)\otimes K]$, where $SA=C_0(0,1)\otimes A$, $[\cdot,\cdot]$ denotes the set of homotopy…

Operator Algebras · Mathematics 2007-05-23 Vladimir Manuilov , Klaus Thomsen

Androulidakis and Skandalis showed how to associate a holonomy groupoid, a smooth convolution algebra and a C*-algebra to any singular foliation. In this note, we consider the singular foliations of a one-dimensional manifold given by…

Operator Algebras · Mathematics 2020-11-18 Michael Francis

We construct in this note a unital properly infinite C*-algebra which is not K$_1$-injective.

Operator Algebras · Mathematics 2016-06-16 Blanchard Etienne

We show that unital simple C*-algebras with tracial topological rank zero which are locally approximated by subhomogeneous C^-algebras can be classified by their ordered $K$-theory. We apply this classification result to show that certain…

Operator Algebras · Mathematics 2007-05-23 Huaxin Lin
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