2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/200401We show that shearfree perfect fluids obeying an equation of state p=(gamma -1) mu are non-rotating or non-expanding under the assumption that the spatial divergence of the magnetic part of the Weyl tensor is zero.11 pagesGeneral Relativity and Quantum Cosmologytext