2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147762Einstein-Vlasov system is solved for a homogeneous isotropic spacetime with positive curvature. In the case of the Universe consisting of massless particles the equation for R(t) is solved analytically.7 pages, LaTex, no figures minor correctionsGeneral Relativity and Quantum Cosmologytext