Exact C*-algebras and the Kirchberg-Phillips Nuclear Embedding Theorem
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Date
2019-08-08
Authors
Sarkowicz, Pawel
Advisor
Marcoux, Laurent
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
A C*-algebra A is exact if the functor A ⊗ min (·) preserves short exact sequences.
This is equivalent to the algebra A having a nuclear faithful *-representation. Exact
C*-algebras are a class of C*-algebras which is much more broad than the class of
nuclear C*-algebras; exactness passes to subalgebras. This property was studied in
great detail by Kirchberg and Wassermann in the early 90’s, and is still interesting
today, for example in the study of exact groups. Exposition will be given to several
results and characterizations related to exact C*-algebras.
We begin by examining certain C*-algebras which play a tremendous role in several
characterizations of exactness in the separable case. The first being the CAR algebra,
which is the UHF algebra corresponding to the infinite tensor product of M 2 . The
second is a family of C*-algebras originally introduced by Cuntz in [9], which are unital,
simple C*-algebras generated by isometries which satisfy a certain relation. We then
proceed to explore exact C*-algebras, initially through the exposition given by Brown
and Ozawa in [6], and then through the work of Kirchberg and Wassermann. Kirchberg
classified the separable exact C*-algebras as those that are subquotients as the CAR
algebra in [18], and Wassermann gave his own proof, the one we choose to follow, in [33].
We finally examine unital, simple, purely infinite C*-algebras and their approximation
properties in order to give a proof of the famous Kirchberg-Phillips nuclear embedding
Theorem, as in [19].
This thesis follows work that was done in a previous USRA term (Winter 2018),
supervised by Laurent Marcoux. During that term I studied nuclear C*-algebras, and
the fact that they are a class of C*-algebras with a positive solution to Kadison’s
similarity problem, of which an exposition can be found in [25].
Description
Keywords
exact c*-algebras, nuclear c*-algebras, c*-algebras, nuclear embedding theorem, Kirchberg-Phillips