Hans Fotsing (African Institute for Mathematical Sciences, Cameroon)
We will discuss riggings on a 1-lightlike submanifold, which have many of the good properties of the Gauss map of non degenerate hypersurfaces. We will also show that for the case of the (n+ 2)-dimensional Minskowski space R^{n+2}_1, the only null Monge hypersurfaces (i.e. graph of a function) x:\Sigma\to R^{n+2}_1 satisfying the eigenvalue equation \Delta x=\lambda x are null hyperplanes. On our way to prove this result, we will show that a smooth function f: R^{n+1}\supset D\to R which is harmonic and whose gradient is of constant norm, is affine.
