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MiS Preprint

Symmetries of null Geometry in Indefinite Kenmotsu Manifolds

Fortuné Massamba


Null hypersurfaces have metrics with vanishing determinants and this degeneracy of these metrics leads to several difficulties. In this paper, null hypersurfaces of indefinite Kenmotsu space forms, tangent to the structure vector field, are studied with specific attention to locally symmetric, semi-symmetric and Ricci semi-symmetric null hypersurfaces. We show that locally symmetric and semi-symmetric null hypersurfaces are totally geodesic and parallel. These also hold for Ricci semi-symmetric null hypersurfaces, under a certain condition.

We prove that, in null Einstein hypersurfaces of an indefinite Kenmotsu space form, tangent to the structure vector field, the local symmetry, semi-symmetry and Ricci semi-symmetry notions are equivalent. For totally contact umbilical null hypersurfaces, we show that there are $\eta$-"Weyl” connections adapted to the induced structure on the null hypersurface.

MSC Codes:
53C15, 53C25, 53C50
Indefinite Kenmostu manifold, Null hypersurface, η- conformal connection

Related publications

2013 Repository Open Access
Fortuné Massamba

Symmetries of null geometry in indefinite Kenmotsu manifolds

In: Mediterranean journal of mathematics, 10 (2013) 2, pp. 1079-1099