# The Bianchi groups are separable on geometrically finite subgroups

### Abstract

Let $d$ be a square free positive integer and $O_d$ the ring of integers in $\mathbf{Q}(\sqrt{-d})$. The main result of this paper is that the groups $\mathrm{PSL}(2,O_d)$ are subgroup separable on geometrically finite subgroups.

Ian Agol

Darren D. Long

Alan W. Reid