4 papers
Planar lattice subsets with minimal vertex boundary
Radhika Gupta, Ivan Levcovitz, Alexander Margolis +1
A subset of vertices of a graph is minimal if, within all subsets of the same size, its vertex boundary is minimal. We give a complete, geometric characterization of minimal sets f…
Surprising circles in Morse boundaries of right-angled Coxeter groups
Marius Graeber, Annette Karrer, Nir Lazarovich +1
We show that the Morse boundary of a right-angled Coxeter group may contain embedded circles that do not arise as the boundary of a Morse Fuchsian subgroup visible in the defining…
Hyperbolic groups that are not commensurably coHopfian
Emily Stark, Daniel J. Woodhouse
Sela proved every torsion-free one-ended hyperbolic group is coHopfian. We prove that there exist torsion-free one-ended hyperbolic groups that are not commensurably coHopfian. In…
The visual boundary of hyperbolic free-by-cyclic groups
Yael Algom-Kfir, Arnaud Hilion, Emily Stark
Let be an atoroidal outer automorphism of the free group . We study the Gromov boundary of the hyperbolic group . We explicitly describe a…