multiplication by ℓ on ℓ2 (G). Following Connes, Mℓ 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 ℓ 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 …