2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/35535The perturbation of an exact solution exhibits a movable transcendental essential singularity, thus proving the nonintegrability. Then, all possible exact particular solutions which may be written in closed form are isolated with the perturbative Painlevé test; this proves the inexistence of any vacuum solution other than the three known ones.14 pages, no figuresGeneral Relativity and Quantum Cosmologytext