Polynomially Bounded Cohomology and Virtually Nilpotent Groups
The application of cyclic cohomology to suitable dense subalgebras of $C^*_r(\Gamma)$ has proven to be an indispensable tool in obtaining information about structures which admit desirable $\Gamma$-actions. On manifolds satisfying $\pi_1(M)\cong\Gamma$, bounding cocyle growth rates is often crucial in proving the well-definedness of certain index theoretic secondary higher invariants. For $\Gamma$ a virtually nilpotent group we show that every delocalized cyclic cocyle class admits a representative of polynomial growth; moreover, this result is extendable to the direct product of a virtually nilpotent group with a word hyperbolic group.