2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/101044We calculate the dimension of the locus of elliptic surfaces over P^1 with a section and a given Picard number, in the corresponding moduli space.Second version; some simplifications, several minor changesAlgebraic Geometry14J27 (Primary); 14D07, 14J10, 14C22 (Secondary)text