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From the 1 of 10 linked papers with an AI index.

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20242026
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10 papers

math.GR2026

Bounded cohomology, quotient extensions, and hierarchical hyperbolicity

Francesco Fournier-Facio, Giorgio Mangioni, Alessandro Sisto

The authors introduce bounded central extensions (those whose Euler class is represented by a bounded cocycle) and prove that such extensions of hierarchically hyperbolic groups (H…

math.GT2026

Coarse embeddings of products of trees as quasi-isometry invariants

Mark Hagen, Alessandro Sisto

We consider the maximal number of factors of a product of bushy trees that can be quasi-isometrically, or even coarsely embedded into various groups of interest, including mapping…

math.GR2026

On automorphisms, quasimorphisms, and coarse automorphisms of acylindrically hyperbolic groups

Ashot Minasyan, Alessandro Sisto, Federico Vigolo

We investigate the action of the automorphism group of an acylindrically hyperbolic group G on its space of homogeneous quasimorphisms, and identify its kernel with the subgroup of…

math.GR2026

A Combinatorial Structure for Many Hierarchically Hyperbolic Spaces

Mark Hagen, Giorgio Mangioni, Alessandro Sisto

The combinatorial hierarchical hyperbolicity criterion is a very useful way of constructing new hierarchically hyperbolic spaces (HHSs). We show that, conversely, HHSs satisfying n…

math.GR2025

Short hierarchically hyperbolic groups II: quotients and the Hopf property for Artin groups

Giorgio Mangioni, Alessandro Sisto

We prove that most Artin groups of large and hyperbolic type are Hopfian, meaning that every self-epimorphism is an isomorphism. The class covered by our result is generic, in the…

math.GR2025

Finite Index Rigidity of Relatively Hyperbolic Groups

Nir Lazarovich, Gon Rahamim, Alessandro Sisto

We prove that, given a torsion-free relatively hyperbolic group G with non-relatively-hyperbolic peripherals, isomorphic finite index subgroups of G have the same index. This appli…