Limits of Baumslag-Solitar groups
  We give a parametrization by $m$-adic integers of the limits of Baumslag-Solitar groups (marked with a canonical set of generators). It is shown to be continuous and injective on the invertible $m$-adic integers. We show that all such limits are extensions of a free group by a lamplighter group and all but possibly one are not finitely presented. Finally, we give presentations related to natural actions on trees. 
Luc Guyot and Yves Stalder