2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/77458Let K be a number field with ring of integers O, and let G be a finite-index subgroup of SL(n,O). Using a classical construction from the geometry of numbers and the theory of modular symbols, we exhibit a finite spanning set for the highest nonvanishing rational cohomology group of G.6 pages, 1 figure, AMS-LaTeX, uses psfrag.sty, incorporates referee's commentsNumber Theory11F75text