Reconstructing a minimal topological dynamical system from a set of return times

TL;DR

This paper explores how minimal topological dynamical systems can be uniquely identified by return times to open sets, especially when the set’s closure lacks symmetries, with implications for Kronecker systems and beyond.

Contribution

It demonstrates that under certain asymmetry conditions, return times uniquely determine minimal systems, extending to Kronecker systems, Nilsystems, and polynomial return times.

Findings

Kronecker systems with same return times are isomorphic if the closure has no symmetries

Return times can determine a Kronecker system up to factorization under asymmetry conditions

The study extends to Nilsystems and polynomial return times, raising questions for other homogeneous spaces

Abstract

We investigate to what extent a minimal topological dynamical system is uniquely determined by a set of return times to some open set. We show that in many situations this is indeed the case as long as the closure of this open set has no non-trivial translational symmetries. For instance, we show that under this assumption two Kronecker systems with the same set of return times must be isomorphic. More generally, we show that if a minimal dynamical system has a set of return times that coincides with a set of return times to some open set in a Kronecker system with translationarily asymmetric closure, then that Kronecker system must be a factor. We also study similar problems involving Nilsystems and polynomial return times. We state a number of questions on whether these results extend to other homogeneous spaces and transitive group actions, some of which are already interesting for finite groups.