1 citations · 1 across the 7 of their papers we have counts for
10 papers
Gruenberg-Kegel graphs: cut groups, rational groups and the Prime Graph Question
Andreas Bächle, Ann Kiefer, Sugandha Maheshwary +1
The Gruenberg-Kegel graph of a group is the undirected graph whose vertices are those primes which occur as the order of an element of the group, and distinct vertices , are…
A dichotomy for integral group rings via higher modular groups as amalgamated products
Andreas Bächle, Geoffrey Janssens, Eric Jespers +2
We show that , the unit group of the integral group ring , either satisfies Kazhdan's property (T) or is, up to commensurability, a non-triv…
Abelianization and fixed point properties of units in integral group rings
Andreas Bächle, Geoffrey Janssens, Eric Jespers +2
Let be a finite group and the unit group of the integral group ring . We prove a unit theorem, namely a characterization of when $\ma…
On Units in Orders in 2-by-2 Matrices over Quaternion Algebras with Rational Center
Ann Kiefer
We generalize an algorithm established in earlier work \cite{algebrapaper} to compute finitely many generators for a subgroup of finite index of an arithmetic group acting properly…
Presentations of Groups Acting Discontinuously on Direct Products of Hyperbolic Spaces
Eric Jespers, Ann Kiefer, Ángel del Río
The problem of describing the group of units of the integral group ring of a finite group has attracted a lot of attention and provid…
Revisiting Poincaré's Theorem on presentations of discontinuous groups via fundamental polyhedra
Eric Jespers, Ann Kiefer, Ángel del Río
We give a new self-contained proof of Poincaré's Polyhedron Theorem on presentations of discontinuous groups of isometries of a Riemann manifold of constant curvature. The proof is…
Dirichlet-Ford domains and Double Dirichlet domains
Eric Jespers, Stanley Orlando Juriaans, Ann Kiefer +2
We continue investigations started by Lakeland on Fuchsian and Kleinian groups which have a Dirichlet fundamental domain that also is a Ford domain in the upper half-space model of…
Describing units of integral group rings up to commensurability
Florian Eisele, Ann Kiefer, Inneke Van Gelder
We restrict the type of -matrices which can occur as simple components in the Wedderburn decomposition of the rational group algebra of a finite group. This results in…
From the Poincaré Theorem to generators of the unit group of integral group rings of finite groups
Eric Jespers, Stanley Orlando Juriaans, Ann Kiefer +2
We give an algorithm to determine finitely many generators for a subgroup of finite index in the unit group of an integral group ring of a finite nilpotent group …
Poincaré Bisectors in Hyperbolic Spaces
Eric Jespers, Stanley Orlando Juriaans, Ann Kiefer +2
We determine explicit formulas for the bisectors used in constructing a Dirichlet fundamental domain in hyperbolic two and three space. They are compared with the isometric spheres…