Uniform homotopy invariance of Roe Index of the signature operator

Abstract

In this paper we study the Roe index of the signature operator of manifolds of bounded geometry. Our main result is the proof of the uniform homotopy invariance of this index. In other words we show that, given an orientation-preserving uniform homotopy equivalence $f:(M,g) \longrightarrow (N,h)$ between two oriented manifolds of bounded geometry, we have that $f_\star(Ind_{Roe}D_M) = Ind_{Roe}(D_N)$. Moreover we also show that the same result holds considering a group $\Gamma$ acting on $M$ and $N$ by isometries and assuming that $f$ is $\Gamma$-equivariant. The only assumption on the action of $\Gamma$ is that the quotients are again manifolds of bounded geometry.