224 research outputs found

    Ideal structure of Cβˆ—C^*-algebras associated with Cβˆ—C^*-correspondences

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    We study the ideal structure of Cβˆ—C^*-algebras arising from Cβˆ—C^*-correspondences. We prove that gauge-invariant ideals of our Cβˆ—C^*-algebras are parameterized by certain pairs of ideals of original Cβˆ—C^*-algebras. We show that our Cβˆ—C^*-algebras have a nice property which should be possessed by generalization of crossed products. Applications to crossed products by Hilbert Cβˆ—C^*-bimodules and relative Cuntz-Pimsner algebras are also discussed.Comment: 34 page

    A class of C^*-algebras generalizing both graph algebras and homeomorphism C^*-algebras I, fundamental results

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    We introduce a new class of C^*-algebras, which is a generalization of both graph algebras and homeomorphism C^*-algebras. This class is very large and also very tractable. We prove the so-called gauge-invariant uniqueness theorem and the Cuntz-Krieger uniqueness theorem, and compute the K-groups of our algebras.Comment: 37 pages, some terminologies changed, for example, C^*-correspondences were called Hilbert C^*-bimodules and topological graphs were called continuous graph

    The ideal structures of crossed products of Cuntz algebras by quasi-free actions of abelian groups

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    We completely determine the ideal structures of the crossed products of Cuntz algebras by quasi-free actions of abelian groups and give another proof of A. Kishimoto's result on the simplicity of such crossed products. We also give a necessary and sufficient condition that our algebras become primitive, and compute the Connes spectra and K-groups of our algebras

    C^*-algebras generated by scaling elements

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    We investigate C^*-algebras generated by scaling elements. We generalize the Wold decomposition and Coburn's theorem on isometries to scaling elements. We also completely determine when the C^*-algebra generated by a scaling element contains an infinite projection.Comment: 8 page

    A class of Cβˆ—C^*-algebras generalizing both graph algebras and homeomorphism Cβˆ—C^*-algebras IV, pure infiniteness

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    This is the final one in the series of papers where we introduce and study the Cβˆ—C^*-algebras associated with topological graphs. In this paper, we get a sufficient condition on topological graphs so that the associated Cβˆ—C^*-algebras are simple and purely infinite. Using this result, we give one method to construct all Kirchberg algebras as Cβˆ—C^*-algebras associated with topological graphs.Comment: 28 page

    A construction of actions on Kirchberg algebras which induce given actions on their K-groups

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    We prove that every action of a finite group all of whose Sylow subgroups are cyclic on the K-theory of a Kirchberg algebra can be lifted to an action on the Kirchberg algebra. The proof uses a construction of Kirchberg algebras generalizing the one of Cuntz-Krieger algebras, and a result on modules over finite groups. As a corollary, every automorphism of the K-theory of a Kirchberg algebra can be lifted to an automorphism of the Kirchberg algebra with same order.Comment: 34 pages, Corrected typo

    A class of C^*-algebras generalizing both graph algebras and homeomorphism C^*-algebras III, ideal structures

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    We investigate the ideal structures of the C^*-algebras arising from topological graphs. We give the complete description of ideals of such C^*-algebras which are invariant under the so-called gauge action, and give the condition on topological graphs so that all ideals are invariant under the gauge action. We get conditions for our C^*-algebras to be simple, prime or primitive. We completely determine the prime ideals, and show that most of them are primitive. Finally, we construct a discrete graph such that the associated C^*-algebra is prime but not primitive.Comment: 47 pages, typos corrected, Sections 11 and 12 Change

    A construction of Cβˆ—C^*-algebras from Cβˆ—C^*-correspondences

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    We introduce a method to define Cβˆ—C^*-algebras from Cβˆ—C^*-correspondences. Our construction generalizes Cuntz-Pimsner algebras, crossed products by Hilbert Cβˆ—C^*-modules, and graph algebras.Comment: 10 pages, to appear in Contemp. Math., Proceedings of the AMS conference "Advances in Quantum Dynamics

    A class of C^*-algebras generalizing both graph algebras and homeomorphism C^*-algebras II, examples

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    We show that the method to construct C^*-algebras from topological graphs, introduced in our previous paper, generalizes many known constructions. We give many ways to make new topological graphs from old ones, and study the relation of C^*-algebras constructed from them. We also prove that our C^*-algebras have a certain characterization. This gives us another definition of our C^*-algebras.Comment: 38 page

    Permutation presentations of modules over finite groups

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    We introduce a notion of permutation presentations of modules over finite groups, and completely determine finite groups over which every module has a permutation presentation. To get this result, we prove that every coflasque module over a cyclic p-group is permutation projective.Comment: 12 page
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