2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/77115It is proved that the geometry of lightlike hypersurfaces of the de Sitter space S^{n+1}_1 is directly connected with the geometry of hypersurfaces of the conformal space C^n. This connection is applied for a construction of an invariant normalization and an invariant affine connection of lightlike hypersurfaces as well as for studying singularities of lightlike hypersurfaces.LaTeX, 32 pages;, to be published in Acta Appl.Math., 1998Differential Geometry53B25text