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The C * -algebra of a Hilbert bimodule

Sergio Doplicher, Claudia Pinzari, Rita Zuccante (1998)

Bollettino dell'Unione Matematica Italiana

Un C * -modulo hilbertiano destro X su una C * -algebra A dotato di uno * -omomorfismo isometrico ϕ : A L A X viene qui considerato come un oggetto X A della C * -categoria degli A -moduli Hilbertiani destri. Come in [11], associamo ad esso una C * -algebra O X A contenente X come un « A -bimodulo hilbertiano in O X A ». Se X è pieno e proiettivo finito O X A è la C * -algebra C * X , la generalizzazione delle algebre di Cuntz-Krieger introdotta da Pimsner [27] (e in un caso particolare da Katayama [31]). Più in generale, C * X è canonicamente immersa...

The closed Friedman world model with the initial and final singularities as a non-commutative space

Michael Heller, Wiesław Sasin (1997)

Banach Center Publications

The most elegant definition of singularities in general relativity as b-boundary points, when applied to the closed Friedman world model, leads to the disastrous situation: both the initial and final singularities form the single point of the b-boundary which is not Hausdorff separated from the rest of space-time. We apply Alain Connes' method of non-commutative geometry, defined in terms of a C*-algebra, to this case. It turns out that both the initial and final singularities can be analysed as...

The closure of the invertibles in a von Neumann algebra

Laura Burlando, Robin Harte (1996)

Colloquium Mathematicae

In this paper we consider a subset  of a Banach algebra A (containing all elements of A which have a generalized inverse) and characterize membership in the closure of the invertibles for the elements of Â. Thus our result yields a characterization of the closure of the invertible group for all those Banach algebras A which satisfy  = A. In particular, we prove that  = A when A is a von Neumann algebra. We also derive from our characterization new proofs of previously known results, namely Feldman...

The Connes-Kasparov conjecture for almost connected groups and for linear p -adic groups

Jérôme Chabert, Siegfried Echterhoff, Ryszard Nest (2003)

Publications Mathématiques de l'IHÉS

Let G be a locally compact group with cocompact connected component. We prove that the assembly map from the topological K-theory of G to the K-theory of the reduced C*-algebra of G is an isomorphism. The same is shown for the groups of k-rational points of any linear algebraic group over a local field k of characteristic zero.

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