# The classification of real purely infinite simple C*-algebras

### Jeffrey L. Boersema

Seattle University, USA### Efren Ruiz

University of Hawaii, Hilo, USA### P.J. Stacey

LaTrobe University, Melbourne, VIC Australia

## Abstract

We classify real Kirchberg algebras using united $K$-theory. Precisely, let $A$ and $B$ be real simple separable nuclear purely infinite C*-algebras that satisfy the universal coefficient theorem such that A_{\mathbb{C} and $B_{\mathbb{C}}$ are also simple. In the stable case, $A$ and $B$ are isomorphic if and only if $K^{CRT}(A) \cong K\crt(B)$. In the unital case, $A$ and $B$ are isomorphic if and only if $(K^{CRT}(A), [1_A]) \cong (K^{CRT}(B), [1_B])$. We also prove that the complexification of such a real C*-algebra is purely infinite, resolving a question left open from [43]. Thus the real C*-algebras classified here are exactly those real C*-algebras whose complexification falls under the classification result of Kirchberg [26] and Phillips[35]. As an application, we find all real forms of the complex Cuntz algebras ${\mathcal{O}}_n$ for $2 \leq n \leq \infty$.

## Cite this article

Jeffrey L. Boersema, Efren Ruiz, P.J. Stacey, The classification of real purely infinite simple C*-algebras. Doc. Math. 16 (2011), pp. 619–655

DOI 10.4171/DM/345