arXiv subjects
Publications and source records attributed to Joël Tossa.
We determine the Lie point symmetries of the Fokker-Planck equation and provide examples of solutions of this equation. The Fokker-Planck equation admits a conserved form, hence there is an auxiliary system associated to this equation and whose point symmetries give rise to potential symmetries of the Fokker-Planck equation.
In this paper, we study Jacobi operators associated to algebraic curvature maps (tensors) on lightlike submanifolds M. We investigate conditions for an induced Rie- mann curvature tensor to be an algebraic curvature tensor on M. We introduce the notion of lightlike Osserman submanifolds and an example of 2-degenerate Osserman metric is given. Finally we give some results of symmetry properties on lightlike hy- persurfaces from Osserman condition.
We give a sufficient condition for a lightlike isotropic submanifold $M$, of dimension $n$, which is not totally geodesic in a semi-Riemannian manifold of constant curvature $c$ and of dimension $n+p (n < p)$, to admit a reduction of codimension. We show that this condition is a necessary and sufficient condition on the first transversal space of $M$. There are basic and non-trivial differences from the Riemannian case, as developed by Dajczer \textit{et al} in (\cite{dajczer}), due to the degenerate metric on $M$. This result extends in some sense,the one in \cite{keti} and \cite{dajczer} to lightlike isotropic submanifolds.