Integrability of Higher-Dimensional Quadratic Tables

Determine whether outer contact billiards over quadratic hypersurfaces remain integrable in projective contact spaces of dimensions higher than three.

Background

In projective three-space, the paper proves complete integrability for quadratic tables and describes the dynamics on invariant quadrics by fixed linear transformations. The appendix explains that higher-dimensional quadratic tables can have additional integrals and branched dynamics, so the persistence of integrability is unresolved.

References

Is the outer contact billiard map over quadratic surfaces still integrable in higher dimensions?

Outer Contact Billiards  (2608.19393 - Caliz et al., 19 Aug 2026) in Section 6, “Open questions,” item 5