Geometry of 1-lightlike submanifolds in anti-de Sitter n-space

In this paper we investigate the differential geometry of 1-lightlike submanifolds in anti-de Sitter n -space as an application of the theory of Legendrian singularities. Based on some theory of lightlike submanifolds, we also introduce the notion of 1-lightlike horospherical Gauss curvature, which is important for us to study the singularities of 1-lightlike horospherical hypersurfaces. Moreover, we discuss the related geometric property of 1-lightlike horospherical hypersurfaces in anti-de Sitter n -space.