|
|
Results 1 - 1 of 1 |
1. CJM 2005 (vol 57 pp. 1056)
| Hyperbolic Group $C^*$-Algebras and Free-Product $C^*$-Algebras as Compact Quantum Metric Spaces Let $\ell$ be a length function on a group $G$, and let $M_{\ell}$
denote the
operator of pointwise multiplication by $\ell$ on $\bell^2(G)$.
Following Connes,
$M_{\ell}$ can be used as a ``Dirac'' operator for $C_r^*(G)$. It defines a
Lipschitz seminorm on $C_r^*(G)$, which defines a metric on the state space of
$C_r^*(G)$. We show that if $G$ is a hyperbolic group and if $\ell$ is
a word-length function on $G$, then the topology from this metric
coincides with the
weak-$*$ topology (our definition of a ``compact quantum metric
space''). We show that a convenient framework is that of filtered
$C^*$-algebras which satisfy a suitable ``Haagerup-type'' condition. We
also use this
framework to prove an analogous fact for certain reduced
free products of $C^*$-algebras.
Categories:46L87, 20F67, 46L09 |

