Epimorphism testing with dihedral targets

Abstract

We consider the problem of deciding whether or not there is an epimorphism from the class of finitely presented groups to a fixed finite group. We show this problem is $\mathsf{NP}$-complete when the target is a non-nilpotent dihedral group. This complements work of Kuperberg and Samperton (2018, Geom. Topol.) who showed the same result when the target is a fixed finite non-abelian simple group. We also include a survey of complexity and reduction results when the source and target are classes of finitely presented groups.

arXiv comment12 pages. The present article was split from arxiv:2501.05283