2 papers
math.GR2025
Schottky pairs on Trees via Continued Fractions and Axial Geometry
Yukun Du, Sa'ar Hersonsky
We give a complete criterion for when two hyperbolic automorphisms of a tree generate a free, discrete subgroup. The decision depends only on three geometric invariants: the transl…
math.GR2025
Busemann-Selberg Functions and Completeness for Dirichlet-Selberg domains in
Yukun Du
We establish a general completeness criterion for Dirichlet-Selberg domains in the symmetric space . By introducing and analyzing Busemann-Selberg functions…