Now showing items 1-5 of 5

  • Accessing the cohomology of discrete groups above their virtual cohomological dimension 

    Rahm, Alexander D. (2014)
    We introduce a method to explicitly determine the Farrell-Tate cohomology of discrete groups. We apply this method to the Coxeter triangle and tetrahedral groups as well as to the Bianchi groups, i.e. PSL_2 over the ring ...
  • The homological torsion of PSL_2 of the imaginary quadratic integers 

    Rahm, Alexander D. (2013)
    The Bianchi groups are the groups (P)SL2 over a ring of integers in an imaginary quadratic number field. We reveal a correspondence between the homological torsion of the Bianchi groups and new geometric invariants, which ...
  • Homology and K-theory of the Bianchi groups 

    Rahm, Alexander D. (2011)
    We reveal a correspondence between the homological torsion of the Bianchi groups and new geometric invariants, which are effectively computable thanks to their action on hyperbolic space. We use it to explicitly compute ...
  • The mod 2 cohomology rings of SL2 of the imaginary quadratic integers 

    Rahm, Alexander D. (Elsevier ScienceDirect, 2015-09-28)
    We establish general dimension formulae for the second page of the equivariant spectral sequence of the action of the SL2 groups over imaginary quadratic integers on their associated symmetric space. By way of doing this, ...
  • On the equivariant K-homology of PSL_2 of the imaginary quadratic integers 

    Rahm, Alexander D. (Association des Annales de l'Institut Fourier, 2016-09)
    We establish formulae for the part due to torsion of the equivariant $K$-homology of all the Bianchi groups (PSL$_2$ of the imaginary quadratic integers), in terms of elementary number-theoretic quantities. To achieve this, ...