2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/63965A projective algebraic surface which is homeomorphic to a ruled surface over a curve of genus $g\ge 1$ is itself a ruled surface over a curve of genus $g$. In this note, we prove the analogous result for projective algebraic manifolds of dimension 4 in case $g\ge 2$.11 pages; To appear in the Annali di Matematica Pura ed ApplicataAlgebraic GeometryGeometric Topology14J35; 14M20; 32Q55text