Lafuente López, JavierAguirre Dabán, Eduardo2023-06-202023-06-202006-03A. Bejancu, Null hypersurfaces of semi-euclidean spaces, Saitama Math. J. 14 (1996) 25–40. M. Kossowski, Fold singularities in pseudo-riemannian geodesic tubes, Proc. Amer. Math. Soc. 95 (1985) 463–469. M. Kossowski, Pseudo-riemannian metric singularities and the extendability of parallel transport, Proc. Amer. Math. Soc. 99 (1987) 147–154. M. Kossowski, M. Kriele, Transverse, type changing, pseudo-riemannian metrics and the extendability of geodesics, Proc. Roy. Soc. London. A 444 (1994) 297–306. M. Kossowski, M. Kriele, The volume blow-up and characteristic classes for transverse, type-changing, pseudo-riemannian metrics, Geom. Dedicata 64 (1997) 1–16. J.C. Larsen, Singular semiriemannian geometry, J. Geom. Phys. 9 (1992) 3–23.0926-224510.1016/j.difgeo.2005.08.001https://hdl.handle.net/20.500.14352/50110Consider a smooth manifold with a smooth metric which changes bilinear type on a hypersurface Σ and whose radical line field is everywhere tangent to Σ. We describe two natural tensors on Σ and use them to describe “integrability conditions” which are similar to the Gauss–Codazzi conditions. We show that these forms control the smooth extendibility to Σ of ambient curvatures.engjournal articlehttp://www.sciencedirect.com/science/article/pii/S0926224505000768http://www.sciencedirect.com/restricted access512Type-changing metricsCurvature extendibilityÁlgebra1201 Álgebra