2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/184942A family of cosmological models is considered which in a certain synchronized system of reference possess flat slices t = const. They are generated from the Einstein-de Sitter universe by a suitable transformation. Under physically reasonable presumptions these transformed models fulfil certain energy conditions.8 pages, LaTeX, no figureGeneral Relativity and Quantum Cosmologytext