Cohomology of congruence subgroups of image II Original Research Article

In a previous paper [Avner Ash, Paul E. Gunnells, Mark McConnell, Cohomology of congruence subgroups of image, J. Number Theory 94 (2002) 181–212] we computed cohomology groups image, where Γ0(N) is a certain congruence subgroup of image, for a range of levels N. In this note we update this earlier work by extending the range of levels and describe cuspidal cohomology classes and additional boundary phenomena found since the publication of [Avner Ash, Paul E. Gunnells, Mark McConnell, Cohomology of congruence subgroups of image, J. Number Theory 94 (2002) 181–212]. The cuspidal cohomology classes in this paper are the first cuspforms for GL(4) concretely constructed in terms of Betti cohomology.