 

Jeffrey L. Boersema and Terry A. Loring
Ktheory for real C*algebras via unitary elements with symmetries view print


Published: 
September 30, 2016 
Keywords: 
topological insulator, semiprojectivity, Ktheory, Etheory, tenfold way 
Subject: 
46L80, 19K99, 81Q99 


Abstract
We prove that all eight KO groups for a real C*algebra can be
constructed from homotopy classes of unitary matrices that respect
a variety of symmetries. In this manifestation of the KO groups,
all eight boudary maps in the 24term exact sequences associated to an
ideal in a real C*algebra can be computed as exponential or
index maps with formulas that are nearly identical to the complex case.


Acknowledgements
This work was partially supported by a grant from the Simons Foundation (208723 to Loring).


Author information
Jeffrey L. Boersema:
Seattle University, Department of Mathematics, Seattle, Washington 98133, USA
boersema@seattleu.edu
Terry A. Loring:
University of New Mexico, Department of Mathematics and Statistics, Albuquerque, New Mexico 87131, USA
loring@math.unm.edu

