2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/64465The existence of closed hypersurfaces of prescribed scalar curvature in globally hyperbolic Lorentzian manifolds is proved provided there are barriers.49 pages, a pdf version can be retrieved from http://www.math.uni-heidelberg.de/studinfo/gerhardt/preprints/, v. 2: dedication added, v. 3 table of contents addedDifferential Geometry35J60, 53C21, 53C44, 53C50, 58J05text