4 papers · 1 filter
A non-Hopfian relatively hyperbolic group with respect to a Hopfian subgroup
Jan Kim, Donghi Lee
We produce an example demonstrating that every finitely generated relatively hyperbolic group with respect to a collection of Hopfian subgroups need not be Hopfian. This answers a…
A family of two generator non-Hopfian groups
Donghi Lee, Makoto Sakuma
We construct -generator non-Hopfian groups , where each has a specific presentation $G_m=\langle a, b \, | \, u_{r_{m,0}}=u_{r_{m,1}}=u_{r_{m,2}}= \…
Epimorphisms from 2-bridge link groups onto Heckoid groups (II)
Donghi Lee, Makoto Sakuma
In Part I of this series of papers, we made Riley's definition of Heckoid groups for 2-bridge links explicit, and gave a systematic construction of epimorphisms from 2-bridge link…
A new proof for small cancellation conditions of 2-bridge link groups
Daewa Kim, Donghi Lee
In this paper, we give a simple proof for the small cancellation conditions of the upper presentations of 2-bridge link groups, which holds the key to the proof of the main result…