Geodesic and billiard flows on quadrics in pseudo-Euclidean spaces: L-A   pairs and Chasles theorem
  In this article we construct L--A representations of geodesic flows on quadrics and of billiard problems within ellipsoids in the pseudo--Euclidean spaces. A geometric interpretation of the integrability analogous to the classical Chasles theorem for symmetric ellipsoids is given. We also consider a generalization of the billiard within arbitrary quadric allowing virtual billiard reflections. 
Bozidar Jovanovic, Vladimir Jovanovic
nlin.SI math.DG