2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/107388Let Gamma\D be an arithmetic quotient of a symmetric space of non-compact type. A spine D_0 is a Gamma-equivariant deformation retraction of D with dimension equal to the virtual cohomological dimension of Gamma. We explicitly construct a spine for the case of Gamma=SU(2,1;Z[i]). The spine is then used to compute the cohomology of Gamma\D with various local coefficients.26 pages, 5 figuresNumber Theory11F57 (Primary), 53C35 (Secondary)text