2 papers
math.GR2025
A non-Hopfian ascending HNN-extension of a finitely presented Hopfian group
Jan Kim, Junseok Kim, Yoonjin Lee
We find a non-Hopfian ascending HNN-extension of a finitely presented Hopfian group by providing an explicit construction. This result addresses an analogous question to the one po…
math.GT2025
Connections between conjugation quandles and their underlying groups via residual finiteness and the Hopf property
Mohamed Elhamdadi, Jan Kim
We prove that if a conjugation quandle is Hopfian, then its underlying group is also Hopfian. We also show that the converse does not hold by providing an example. This highlights…