On the Group of Transformations of Constructible Euclidean Planes with Preserve a Single Distance.
On the incidence structures of polar spaces and quadrics.
On the planar translation structures
On Veldkamp lines.
One characterization of special translation planes
One configurational characterization of Ostrom nets
Bz the quadrileteral condition in a given net there is meant the following implication: If are arbitrary points, no three of them lie on the same line, with coll (collinearity) for any five from six couples then there follows the collinearity coll for the remaining couple . In the article there is proved the every net satisfying the preceding configuration condition is necessarity the Ostrom net (i.e., the net over a field). Conversely, every Ostrom net satisfies the above configuration...
One generalization of quasifield
One generalization of the fourth harmonic point (Preliminary communication)
Opérations sur les cartes et métamorphoses de la catégorie des G-ensembles.
We call metamorphosis of a given category an autoequivalence functor up to within natural equivalence. We show that, given a group G, the group of metamorphoses of the category of G-sets (as well as the corresponding group for ?sufficiently big? subcategories) may be naturally identified to the group of outer automorphism of G. We get by this way a natural description of a group of known operations on tessellations of a surface: the identity operation, the Poincaré duality, and four others which...
Orientierung in angeordneten affinen Räumen
Orthogonal, symplectic and unitary polar spaces sub-weakly embedded in projective space
Ovals and non-ovoidal Laguerre planes.
Ovoids of the Hermitian surface in odd characteristic.
and line-transitive linear spaces.
Pappus' theorem for ring-geometries.
Pappus's theorem and the modular group
Partitionen Liescher und algebraischer Gruppen.
Pentagramma mirificum and elliptic functions (Napier, Gauss, Poncelet, Jacobi, ...)
We give an exposition of unpublished fragments of Gauss where he discovered (using a work of Jacobi) a remarkable connection between Napier pentagons on the sphere and Poncelet pentagons on the plane. As a corollary we find a parametrization in elliptic functions of the classical dilogarithm five-term relation.
Piani di traslazione derivabili
Places of alternative fields