2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/226317The possibility of obtaining an open set of regular cosmological models is discussed. Cylindrical stiff perfect fluid cosmologies are studied in detail. The condition for geodesic completeness is easy to check. A large family of non-singular models is found therein.4 pp. Proceedings of ERE 2002, Maó, SpainGeneral Relativity and Quantum Cosmologytext