2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/196857Any three-dimensional Riemannian metric can be locally obtained by deforming a constant curvature metric along one direction. The general interest of this result, both in geometry and physics, and related open problems are stressed.14 pages, LaTeXGeneral Relativity and Quantum Cosmologytext