On the dynamics of extensions of free-abelian times free groups endomorphisms to the completion

TL;DR

This paper investigates the conditions under which endomorphisms of free-abelian times free groups are uniformly continuous, explores their extensions to the completion, and analyzes the dynamics of infinite points, showing they are either periodic or wandering.

Contribution

It establishes a link between uniform continuity and preservation of coarse-median structures, and characterizes the dynamics of infinite points in these groups.

Findings

Uniform continuity characterized by preservation of coarse-median.

Count of orbits for fixed and periodic points under endomorphisms.

Infinite points are either periodic or wandering, leading to asymptotically periodic dynamics.

Abstract

We obtain conditions of uniform continuity for endomorphisms of free-abelian times free groups for the product metric defined by taking the prefix metric in each component and establish an equivalence between uniform continuity for this metric and the preservation of a coarse-median, which was recently introduced by Fioravanti. Considering the extension of an endomorphism to the completion we count the number of orbits for the action of the subgroup of fixed points (resp. periodic) points on the set of infinite fixed (resp. periodic) points. Finally, we study the dynamics of infinite points: for some endomorphisms, defined in a precise way, fitting a classification given by Delgado and Ventura, we prove that every infinite point is either periodic or wandering, which implies that the dynamics is asymptotically periodic. We also prove the latter for the case of automorphisms.