Isometric Lightlike Immersions in \( \mathbb {R}\times \mathbb {Q}^{n+1}_{c,1}\)
摘要
In this work we establish a form of the fundamental theorem regarding immersions of lightlike hypersurfaces in the Cartesian product \( \mathbb {R}\times \mathbb {Q}^{n+1}_{c,1}\) , where \(\mathbb {Q}^{n+1}_{c,1}\) denotes a Lorentzian space form of constant sectional curvature c. Namely, we establish necessary and sufficient conditions for the existence of an isometric immersion \(\phi \) of a smooth \((n+1)\) -dimensional manifold M endowed with a degenerate metric g on \( \mathbb {R}\times \mathbb {Q}^{n+1}_{c,1}\) , provided that \(\partial _t\in \varGamma (\phi (M))\) .