Approximating Novikov-Shubin numbers of virtually cyclic coverings

Abstract

We assign real numbers to finite sheeted coverings of compact CW complexes designed as finite counterparts to the Novikov-Shubin numbers. We prove an approximation theorem in the case of virtually cyclic fundamental groups employing methods from Diophantine approximation.

arXiv commentFinal version to appear in Groups Geom. Dyn., 17 pages