Paterson compactifications, inverse limits and shadowing for Deaconu-Renault systems

TL;DR

This paper introduces a new ultrametric and inverse-limit framework for Deaconu-Renault systems, extending shadowing theory from compact to locally compact zero-dimensional spaces.

Contribution

It develops an explicit ultrametric compactification, constructs an inverse-limit space incorporating finite and infinite orbits, and characterizes shadowing in this noncompact setting.

Findings

Constructed a compatible ultrametric on the Paterson compactification.

Described the inverse-limit space including finite configurations.

Proved shadowing equivalence between inverse-limit and base systems under separation conditions.

Abstract

We develop a new metric and inverse-limit framework for Deaconu-Renault systems arising from local homeomorphisms between open subsets of locally compact zero-dimensional spaces. Our starting point is the Paterson-type compactification of infinite product spaces, which underlies several symbolic and groupoid models, including one-sided shifts over infinite alphabets and path spaces of graphs and higher-rank graphs. We construct an explicit compatible ultrametric on this compactification and give a concrete description of its generalized cylinder topology and convergence. Within this framework, we introduce an inverse-limit-type space naturally associated to a Deaconu-Renault system. In contrast with the classical compact theory, the correct inverse-limit object must incorporate not only infinite backward orbits but also finite configurations arising as limits of such orbits. This produces a canonical shift system extending the original dynamics. We then study shadowing in the ultrametric setting. For spaces admitting tame defining sequences, we characterize shadowing in terms of the defining partitions, extending the topological description of shadowing from compact zero-dimensional dynamics to the locally compact setting relevant for Deaconu-Renault systems. As a main application, we prove a transfer theorem showing, under a separation property expressed through uniformly contracting inverse branches, that shadowing for the inverse-limit Deaconu-Renault system is equivalent to shadowing for the compactified base system. This provides a noncompact inverse-limit shadowing theory for a broad class of partially defined local-homeomorphism dynamics.