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Simple ${\bi C}^*$-algebras arising from ${\beta}$-expansion of real numbers

Published online by Cambridge University Press:  01 August 1998

YOSHIKAZU KATAYAMA
Affiliation:
Division of Applied Mathematics, Osaka Kyoiku University, Kasiwara, 582, Japan
KENGO MATSUMOTO
Affiliation:
Department of Mathematics, Joetsu University of Education, Joetsu 943, Japan
YASUO WATATANI
Affiliation:
Graduate School of Mathematics, Kyushu University, Ropponmatsu, Fukuoka 810, Japan

Abstract

Given a real number $\beta > 1$, we construct a simple purely infinite $C^*$-algebra ${\cal O}_{\beta}$ as a $C^*$-algebra arising from the $\beta$-subshift in the symbolic dynamics. The $C^*$-algebras $\{{\cal O}_{\beta} \}_{1<\beta \in {\Bbb R}}$ interpolate between the Cuntz algebras $\{{\cal O}_n\}_{1 < n \in {\Bbb N}}$. The K-groups for the $C^*$-algebras ${\cal O}_{\beta}$, $1 < \beta \in {\Bbb R}$, are computed so that they are completely classified up to isomorphism. We prove that the KMS-state for the gauge action on ${\cal O}_{\beta}$ is unique at the inverse temperature $\log \beta$, which is the topological entropy for the $\beta$-shift. Moreover, ${\cal O}_{\beta}$ is realized to be a universal $C^*$-algebra generated by $n-1=[\beta]$ isometries and one partial isometry with mutually orthogonal ranges and a certain relation coming from the sequence of $\beta$-expansion of $1$.

Type
Research Article
Copyright
© 1998 Cambridge University Press

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