Quadratic forms of rank 1, closed zones and laminae
  For a given lattice, we establish an equivalence involving a closed zone of the corresponding Voronoi polytope, a lamina hyperplane of the corresponding Delaunay partition and a quadratic form of rank 1 being an extreme ray of the corresponding L-type domain. 
Michel Deza (1) and Viatcheslav Grishukhin (2) ((1) Ecole Normale   Superieure, Paris, (2) CEMI, Russian Academy of Sciences...