TITLE:
On the Curvature and Injectivity Radius Growth and Topology of Null Hypersurfaces in Lorentzian Manifolds
AUTHORS:
Ménédore Karimumuryango, Domitien Ndayirukiye, Nibaruta Gilbert
KEYWORDS:
Injectivity Radius, Rigging, Topology, Lorentzian Manifold, Lightlike Hypersurface
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.13 No.9,
September
26,
2025
ABSTRACT: We consider an associated Riemannian metric induced by a rigging defined on a neighborhood of the null hypersurface in a Lorentzian manifold, and we connect this null geometry with the associated Riemannian geometry. Using a rigging defined on some open set containing the lightlike hypersurface, we introduce a global geometric invariant
Ra
d
ζ
(
M
)
related to injectivity radius to a closed complete noncompact null hypersurface in a Lorentzian manifold. Using some comparison theorems from non-degenerated geometry, we give the relationship between geometry and topology of a closed complete noncompact null hypersurface with associated Riemannian metric and the asymptotic properties of injectivity radiuses at infinity.