Jan Essert

  1. Homological stability for classical groups.

    Authors: Jan Essert
    Subjects: K-Theory and Homology
    Abstract

    Associated to every group with a weak spherical BN pair of rank n+1 with an
    appropriate rank n subgroup, we construct a relative spectral sequence
    involving group homology of Levi subgroups of both groups. Using the fact that
    such Levi subgroups frequently split as semidirect products of smaller groups,
    we prove homological stability results for unitary groups over division rings
    with infinite centre as well as for special linear and special orthogonal
    groups over infinite fields.

  2. Homological stability for classical groups.

    Authors: Jan Essert
    Subjects: K-Theory and Homology
    Abstract

    Associated to every group with a weak spherical BN pair of rank n+1 with an
    appropriate rank n subgroup, we construct a relative spectral sequence
    involving group homology of Levi subgroups of both groups. Using the fact that
    such Levi subgroups frequently split as semidirect products of smaller groups,
    we prove homological stability results for unitary groups over division rings
    with infinite centre as well as for special linear and special orthogonal
    groups over infinite fields.

  3. A geometric construction of panel-regular lattices in buildings of types ~A_2 and ~C_2.

    Authors: Jan Essert
    Subjects: Group Theory
    Abstract

    Using Singer polygons, we construct locally finite affine buildings of types
    ~A_2 and ~C_2 which admit uniform lattices acting regularly on panels. This
    construction produces very explicit descriptions of these buildings as well as
    very short presentations of the lattices. All but one of the ~C_2-buildings are
    necessarily exotic. Integral and rational group homology for the lattices is
    also calculated.

RSS-материал