- Research Article
5
- 10.1016/j.jalgebra.2010.05.009
The acyclic group dichotomy
- Jun 10, 2010
- Journal of Algebra
- A.J Berrick
The acyclic group dichotomy
We discuss two classes of acyclic groups that are commutator subgroups of finitely presented groups with infinite cyclic abelianization. The first is algebraic and includes groups first exhibited by Baumslag and Gruenberg, of which it is shown that Epstein’s acyclic group is as pecial case. The second class is geometric, and is shown to include a number of wild arc groups in the literature.
The acyclic group dichotomy
The acyclic group dichotomy
Bielliptic ball quotient compactifications and lattices in PU(2,1) with finitely generated commutator subgroup
We construct two infinite families of ball quotient compactifications birational to bielliptic surfaces. For each family, the volume spectrum of the associated noncompact finite volume ball quotient surfaces is the set of all positive integral multiples of 8 3π 2 , i.e., they attain all possible volumes of complex hyperbolic 2-manifolds. The surfaces in one of the two families all have 2-cusps, so that we can saturate the entire volume spectrum with 2-cusped manifolds. Finally, we show that the associated neat lattices have infinite abelianization and finitely generated commutator subgroup. These appear to be the first known nonuniform lattices in PU(2,1), and the first infinite tower, with this property.
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