Abstract
Given a group G and an endomorphism of G, two elements are said to be -conjugate if for some The number of equivalence classes for this relation is the Reidemeister number of The set is called the Reidemeister spectrum of G. We investigate Reidemeister numbers and spectra on direct products of finitely many groups and determine what information can be derived from the individual factors.
2020 MATHEMATICS SUBJECT CLASSIFICATION:
Acknowledgments
The author thanks Karel Dekimpe and the anonymous referee for their useful remarks and suggestions, in particular for their examples of concrete groups to which the results apply.