3 papers
math.GR2025
On commensurators of free groups and free pro-p groups
Yiftach Barnea, Mikhail Ershov, Adrien Le Boudec +3
We study the commensurators of free groups and free pro- groups, as well as certain subgroups of these. We prove that the commensurator of a non-abelian free group of…
math.GR2025
On groups that can be covered by conjugates of finitely many cyclic or procyclic subgroups
Yiftach Barnea, Rachel Camina, Mikhail Ershov +1
Given a discrete (resp. profinite) group , we define to be the smallest number of cyclic (resp. procyclic) subgroups of whose conjugates cover . In this paper we…
math.GR2025
The normal growth of linear groups over formal power serieses
Yiftach Barnea, Jan-Christoph Schlage-Puchta
Put $R=\F[[t_1, \ldots, t_d]])$. We estimate the number of normal subgroups of $\mathrm{SL}_2^1(\F[[t_1, \ldots, t_d]])$ for , the number of ideals in the Lie algebra $\Lie(R)…