  Baumslag's group is a finitely presented metabelian group with a Z \wr Z
subgroup. There is an analogue with an additional torsion relation in which
this subgroup becomes C_m \wr Z. We prove that Baumslag's group has an
exponential Dehn function. This contrasts with the torsion analogues which have
quadratic Dehn functions. v.2: version for publication, incorporating referee's
suggestions.
