2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/77736We show that for certain arithmetic groups, geometrically finite subgroups are the intersection of finite index subgroups containing them. Examples are the Bianchi groups and the Seifert-Weber dodecahedral space. In particular, for manifolds commensurable with these groups, immersed incompressible surfaces lift to embeddings in a finite sheeted covering.19 pagesGeometric Topologytext