Cuntz-Krieger algebras associated with Hilbert $C^*$-quad modules of   commuting matrices
  Let ${\cal O}_{{\cal H}^{A,B}_\kappa}$ be the $C^*$-algebra associated with the Hilbert $C^*$-quad module arising from commuting matrices $A,B$ with entries in $\{0,1\}$. We will show that if the associated tiling space $X_{A,B}^\kappa$ is transitive, the $C^*$-algebra ${\cal O}_{{\cal H}^{A,B}_\kappa}$ is simple and purely infinite. In particulr, for two positive integers $N,M$, the $K$-groups of the simple purely infinite $C^*$-algebra ${\cal O}_{{\cal H}^{[N],[M]}_\kappa}$ are computed by using the Euclidean algorithm. 
Kengo Matsumoto
math.OA