Homeomorphisms of the space of non-zero integers with the Kirch topology

Abstract

The $Golomb$ (resp. $Kirch$) topology on the set $\mathbb Z^\bullet$ of nonzero integers is generated by the base consisting of arithmetic progressions $a+b\mathbb Z=\{a+bn:n\in\mathbb Z\}$ where $a\in\mathbb Z^\bullet$ and $b$ is a (square-free) number, coprime with $a$. In 2019 Dario Spirito proved that the space of nonzero integers endowed with the Golomb topology admits only two self-homeomorphisms. In this paper we prove an analogous fact for the space of nonzero integers endowed with the Kirch topology: it also admits exactly two self-homeomorphisms.