On the extension of unitary group isomorphisms of unital UHF-algebras

2015 ◽  
Vol 26 (08) ◽  
pp. 1550061
Author(s):  
Ahmed Al-Rawashdeh

H. Dye showed that an isomorphism between the (discrete) unitary groups in two factors not of type In is implemented by a linear (or a conjugate linear) *-isomorphism of the factors. If φ is an isomorphism between the unitary groups of two unital C*-algebras, it induces a bijective map θφ between the sets of projections. For certain UHF-algebras, we construct an automorphism φ of their unitary group, such that θφ does not preserve the orthogonality of projections. For a large class of unital finite C*-algebras, we show that θφ is always an orthoisomorphism. If φ is a continuous automorphism of the unitary group of a UHF-algebra A, we show that φ is implemented by a linear or a conjugate linear *-automorphism of A.

2002 ◽  
Vol 14 (07n08) ◽  
pp. 649-673 ◽  
Author(s):  
AKITAKA KISHIMOTO

We present two types of result for approximately inner one-parameter automorphism groups (referred to as AI flows hereafter) of separable C*-algebras. First, if there is an irreducible representation π of a separable C*-algebra A such that π(A) does not contain non-zero compact operators, then there is an AI flow α such that π is α-covariant and α is far from uniformly continuous in the sense that α induces a flow on π(A) which has full Connes spectrum. Second, if α is an AI flow on a separable C*-algebra A and π is an α-covariant irreducible representation, then we can choose a sequence (hn) of self-adjoint elements in A such that αt is the limit of inner flows Ad eithn and the sequence π(eithn) of one-parameter unitary groups (referred to as unitary flows hereafter) converges to a unitary flow which implements α in π. This latter result will be extended to cover the case of weakly inner type I representations. In passing we shall also show that if two representations of a separable simple C*-algebra on a separable Hilbert space generate the same von Neumann algebra of type I, then there is an approximately inner automorphism which sends one into the other up to equivalence.


1994 ◽  
Vol 14 (2) ◽  
pp. 1500-1509
Author(s):  
H Harada ◽  
E Takahashi ◽  
S Itoh ◽  
K Harada ◽  
T A Hori ◽  
...  

Interferon regulatory factor 1 (IRF-1) and IRF-2 are structurally similar DNA-binding factors which were originally identified as regulators of the type I interferon (IFN) system; the former functions as a transcriptional activator, and the latter represses IRF-1 function by competing for the same cis elements. More recent studies have revealed new roles of the two factors in the regulation of cell growth; IRF-1 and IRF-2 manifest antioncogenic and oncogenic activities, respectively. In this study, we determined the structures and chromosomal locations of the human IRF-1 and IRF-2 genes and further characterized the promoters of the respective genes. Comparison of exon-intron organization of the two genes revealed a common evolutionary structure, notably within the exons encoding the N-terminal portions of the two factors. We confirmed the chromosomal mapping of the human IRF-1 gene to 5q31.1 and newly assigned the IRF-2 gene to 4q35.1, using fluorescence in situ hybridization. The 5' regulatory regions of both genes contain highly GC-rich sequences and consensus binding sequences for several known transcription factors, including NF-kappa B. Interestingly, one IRF binding site was found within the IRF-2 promoter, and expression of the IRF-2 gene was affected by both transient and stable IRF-1 expression. In addition, one potential IFN-gamma-activated sequence was found within the IRF-1 promoter. Thus, these results may shed light on the complex gene network involved in regulation of the IFN system.


2013 ◽  
Vol 65 (1) ◽  
pp. 52-65
Author(s):  
Erik Christensen ◽  
Allan M. Sinclair ◽  
Roger R. Smith ◽  
Stuart White
Keyword(s):  
Type I ◽  

AbstractIn this paper we consider near inclusions of C*-algebras. We show that if B is a separable type I C*-algebra and A satisfies Kadison's similarity problem, then A is also type I. We then use this to obtain an embedding of A into B.


2003 ◽  
Vol 6 ◽  
pp. 162-197 ◽  
Author(s):  
Peter A. Brooksbank

AbstractIn this paper, the author presents a new algorithm to recognise, constructively, when a given black-box group is a homomorphic image of the unitary group SU(d, q) for known d and q. The algorithm runs in polynomial time, assuming the existence of oracles for handling SL(2, q) subgroups, and for computing discrete logarithms in cyclic groups of order q ± 1.


Author(s):  
Tattwamasi Amrutam

Abstract We show that for a large class of actions $\Gamma \curvearrowright \mathcal{A}$ of $C^*$-simple groups $\Gamma $ on unital $C^*$-algebras $\mathcal{A}$, including any non-faithful action of a hyperbolic group with trivial amenable radical, every intermediate $C^*$-subalgebra $\mathcal{B}$, $C_{\lambda }^*(\Gamma )\subseteq \mathcal{B} \subseteq \mathcal{A}\rtimes _{r}\Gamma $, is of the form $\mathcal{A}_1\rtimes _{r}\Gamma $, where $\mathcal{A}_1$ is a unital $\Gamma $-$C^*$-subalgebra of $\mathcal{A}$.


2001 ◽  
Vol 12 (07) ◽  
pp. 813-845 ◽  
Author(s):  
HAJIME FUTAMURA ◽  
NOBUHIRO KATAOKA ◽  
AKITAKA KISHIMOTO

We prove that the pure state space is homogeneous under the action of the automorphism group (or a certain smaller group of approximately inner automorphisms) for a fairly large class of simple separable nuclear C*-algebras, including the approximately homogeneous C*-algebras and the class of purely infinite C*-algebras which has been recently classified by Kirchberg and Phillips. This extends the known results for UHF algebras and AF algebras by Powers and Bratteli.


2012 ◽  
Vol 56 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Alejandro Adem ◽  
F. R. Cohen ◽  
José Manuel Gómez

AbstractWe study the space of commuting elements in the central product Gm,p of m copies of the special unitary group SU(p), where p is a prime number. In particular, a computation for the number of path-connected components of these spaces is given and the geometry of the moduli space Rep(ℤn, Gm,p) of isomorphism classes of flat connections on principal Gm,p-bundles over the n-torus is completely described for all values of n, m and p.


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