On an analogue of the Hurewicz theorem for mean dimension

Abstract

The Hurewicz theorem is a fundamental result in classical dimension theory concerning continuous maps which lower topological dimension. We study whether or not its analogue holds for mean dimension of dynamical systems. Our first main result shows that an analogue of the Hurewicz theorem does not hold for mean dimension in general. Our second main result shows that it holds true if a base system has zero mean dimension.