2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/229290We survey our joint work with Avner Ash and Mark McConnell that computationally investigates the cohomology of conguence subgroups of SL_4 (\Z). This is based on a talk given at the 2009 RIMS conference "Automorphic representations, automorphic L-functions and arithmetic."Number Theory11F75text