| Autor: |
PING WONG NG, ROBERT, LEONEL, SKOUFRANIS, PAUL |
| Předmět: |
|
| Zdroj: |
Transactions of the American Mathematical Society; Aug2018, Vol. 370 Issue 8, p5725-5759, 35p |
| Abstrakt: |
We investigate the closed convex hull of unitary orbits of selfadjoint elements in arbitrary unital C*-algebras. Using a notion of majorization against unbounded traces, a characterization of these closed convex hulls is obtained. Furthermore, for C*-algebras satisfying Blackadar's strict comparison of positive elements by traces or for collections of C*-algebras with a uniform bound on their nuclear dimension, an upper bound for the number of unitary conjugates in a convex combination required to approximate an element in the closed convex hull within a given error is shown to exist. This property, however, fails for certain "badly behaved" simple nuclear C*-algebras. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
