The classification of SPG-systems of index 2.
The generating rank of the symplectic line-Grassmannian.
The geometry of null systems, Jordan algebras and von Staudt's theorem
We characterize an important class of generalized projective geometries by the following essentially equivalent properties: (1) admits a central null-system; (2) admits inner polarities: (3) is associated to a unital Jordan algebra. These geometries, called of the first kind, play in the category of generalized projective geometries a rôle comparable to the one of the projective line in the category of ordinary projective geometries. In this general set-up, we prove an analogue of von Staudt’s...
The hyperplanes of .
The universal embedding of the near polygon .
The valuations of the near octagon .
The valuations of the near polygon G.