Metric mean dimension via subshifts of compact type
Gustavo Pessil
TL;DR
This paper develops a comprehensive framework for metric mean dimension in the setting of subshifts of compact type and extends it to discontinuous maps. It proves that the metric mean dimension is invariant between a map and its inverse limit, generalizing Bowen’s entropy relation, and shows that mdim_M for discontinuous maps can be defined via the closure of the associated transition subshift. The work then builds a variational principle connecting Friedland’s entropy for free semigroup actions with the CRV random-walk approach to mdim_M, and demonstrates that zero-complexity maps can generate positive mdim_M under semigroup dynamics. Applications include showing that the Gauss map and induced Manneville–Pomeau maps have mdim_M equal to the box dimension of their discontinuity sets, tying mdim_M to the pressure’s critical exponent s_ty and to geometric features of the discontinuities. Collectively, the results provide a robust bridge between symbolic dynamics, thermodynamic formalism, and geometric notions of dimension for a broad class of (possibly discontinuous) dynamical systems.
Abstract
We investigate the metric mean dimension of subshifts of compact type. We prove that the metric mean dimensions of a continuous map and its inverse limit coincide, generalizing Bowen's entropy formula. Building upon this result, we extend the notion of metric mean dimension to discontinuous maps in terms of suitable subshifts. As an application, we show that the metric mean dimension of the Gauss map and that of induced maps of the Manneville-Pomeau family is equal to the box dimension of the corresponding set of discontinuity points, which also coincides with a critical parameter of the pressure operator associated to the geometric potential.
