Closed Convex Hulls of Unitary Orbits in Certain Simple Real Rank Zero C* -algebras

Ng, P.W. ; Skoufranis, P.

Canadian journal of mathematics, Tome 69 (2017) no. 5, pp. 1109-1142

Résumé

In this paper, we characterize the closures of convex hulls of unitary orbits of self-adjoint operators in unital, separable, simple ${{\text{C}}^{*}}$ -algebras with non-trivial tracial simplex, real rank zero, stable rank one, and strict comparison of projections with respect to tracial states. In addition, an upper bound for the number of unitary conjugates in a convex combination needed to approximate a self-adjoint are obtained.

Détail

DOI : 10.4153/CJM-2016-045-5

Mots-clés : 46L05, convex hull of unitary orbits, real rank zero C* -algebras simple, eigenvalue function, majorization

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