5 papers
Asymptotically rigid mapping class groups III: Presentations and isomorphisms
Anthony Genevois, Anne Lonjou, Christian Urech
This article is dedicated to the computation of an explicit presentation of some asymptotically rigid mapping class groups, namely the braided Higman-Thompson groups. To do so, we…
Survey on Cremona groups from a median geometric point of view
Anne Lonjou
This expository article builds on lecture notes from a minicourse entitled "Cremona groups and CAT(0) cube complexes" and given by the author as part of the 2023 Riverside Workshop…
On a Theorem by Lin and Shinder through the Lens of Median Geometry
Anthony Genevois, Anne Lonjou, Christian Urech
Recently, Lin and Shinder constructed non-trivial homomorphisms from Cremona groups of rank >2 to \mathbb{Z} using motivic techniques. In this short note we propose an alternative…
Asymptotically rigid mapping class groups II: strand diagrams and nonpositive curvature
Anthony Genevois, Anne Lonjou, Christian Urech
In this article, we introduce a new family of groups, called Chambord groups and constructed from braided strand diagrams associated to specific semigroup presentations. It include…
Finitely generated subgroups of algebraic elements of plane Cremona groups are bounded
Anne Lonjou, Piotr Przytycki, Christian Urech
We prove that any finitely generated subgroup of the plane Cremona group consisting only of algebraic elements is of bounded degree. This follows from a more general result on `dec…