GLASGOW MATHEMATICAL JOURNAL, vol.41, pp.271-281, 1999 (Journal Indexed in SCI)
Article / Article
Title of Journal :
GLASGOW MATHEMATICAL JOURNAL
We prove that the conditions R . R = 0 and R . S = 0 are equivalent for hypersurfaces of a 5-dimensional semi-Riemannian space form N-5(c). This solves a problem by P.J. Ryan in the case of hypersurfaces of dimension 4 in semi-Riemannian space forms.