On the critical exponent of infinitely generated Veech groups

Infinitely Generated Veech Groups

We give a positive response to a question of W. Veech: Infinitely generated Veech groups do exist.

Geometry of Infinitely Generated Veech Groups

Veech groups uniformize Teichmüller geodesics in Riemann moduli space. We gave examples of infinitely generated Veech groups; see Duke Math. J. 123 (2004), 49–69. Here we show that the associated Teichmüller geodesics can even have both infinitely many cusps and infinitely many infinite ends.

Infinite Translation Surfaces with Infinitely Generated Veech Groups

O ct 2 00 4 GEOMETRY OF INFINITELY GENERATED VEECH GROUPS

Veech groups uniformize Teichmüller geodesic curves in Riemann moduli space. Recently, examples of infinitely generated Veech groups have been given. We show that these can even have infinitely many cusps and infinitely many infinite ends. We further show that examples exist for which each direction of an infinite end is the limit of directions of inequivalent infinite ends.

Infinitely Generated Free Nilpotent Groups: Completeness of the Automorphism Groups

Baumslag conjectured in the 1970s that the automorphism tower of a finitely generated free group (free nilpotent group) must be very short. Dyer and Formanek [9] justified the conjecture concerning finitely generated free groups in the “sharpest sense” by proving that the automorphism group Aut(Fn) of a non-abelian free group Fn of finite rank n is complete. Recall that a group G is said to be ...