3 papers
math.GR2026
Outer automorphism groups of hyperbolic groups, bounded extensions, and hierarchical hyperbolicity
Ervin Hadziosmanovic, Giorgio Mangioni
We prove that the outer automorphism group of a one-ended hyperbolic group is virtually a hierarchically hyperbolic group (HHG), under mild orientability conditions on the associat…
math.GR2026
A combination theorem for the twist conjecture for Artin groups
Oli Jones, Giorgio Mangioni, Giovanni Sartori
We reduce a strong version of the twist conjecture for Artin groups to Artin groups whose defining graphs have no separating vertices. This produces new examples of Artin groups sa…
math.GR2025
JSJ splittings for all Artin groups
Oli Jones, Giorgio Mangioni, Giovanni Sartori
We prove that an Artin group splits over infinite cyclic subgroups if and only if its defining graph has a separating vertex, and explicitly construct a JSJ decomposition over infi…