Finitely summable $\gamma$-elements for word-hyperbolic groups

Abstract

We present two explicit combinatorial constructions of finitely summable reduced "Gamma"-elements $\gamma_r\,\in\,KK(C^*_r(\Gamma),{\mathbb C})$ for any word-hyperbolic group $(\Gamma,S)$ and obtain summability bounds for them in terms of the cardinality of the generating set $S\subset\Gamma$ and the hyperbolicity constant of the associated Cayley graph.