Representing Countable Groups by Homeomorphism Groups in Hilbert Space.
Representing subgroups of finitely presented groups by quotient subgroups.
Rescuing the Whitehead Method for Free Products, I: Peak Reduction.
Rescuing the Whitehead Method for Free Products, II: The Algorithm.
Réseaux de Coxeter-Davis et commensurateurs
For each integer and each finite graph , we construct a Coxeter group and a non positively curved polygonal complex on which acts properly cocompactly, such that each polygon of has edges, and the link of each vertex of is isomorphic to . If is a “generalized -gon”, then is a Tits building modelled on a reflection group of the hyperbolic plane. We give a condition on for to be non enumerable (which is satisfied if is a thick classical generalized -gon). On the other hand,...
Residually finite PSP-groups
Restoration of structure
Restricted set addition in groups. II: A generalization of the Erdős-Heilbronn conjecture.
Rigidity of graph products of groups.
Rigidity of skew-angled Coxeter groups.
Rings of Fricke Characters and Automorphism Groups of Free Groups.
Root systems for two dimensional complex reflection groups.
R-trees and the Bieri-Neumann-Strebel invariant.
Let G be a finitely generated group. We give a new characterization of its Bieri-Neumann-Strebel invariant Σ(G), in terms of geometric abelian actions on R-trees. We provide a proof of Brown's characterization of Σ(G) by exceptional abelian actions of G, using geometric methods.