Torsion in the cohomology of congruence subgroups of SL(4,Z) and Galois representations

Avner Ash, Paul E. Gunnells, Mark McConnell

We report on the computation of torsion in certain homology theories of congruence subgroups of SL(4,Z). Among these are the usual group cohomology, the Tate-Farrell cohomology, an…