The classification of compact hyperbolic Coxeter d-polytopes with d + 2 facets.
The classification of compact right chain rings.
The classification of generalized quadrangles with two translation points.
The Classification of Quasi-Regular Polyhedra of Genus 2.
The classification of SPG-systems of index 2.
The classification of spreads in admitting linear groups of order . II: Even order.
The classification of subplane covered nets.
The Coexistence of Elations and Homologies.
The Collineation Groups of Derived Translation Planes. II.
The combinatorial structure of trigonometry.
The combinatorially regular polyhedra of index 2.
The Complexity and Construction of Many Faces in Arrangements of Lines and of Segments.
The Complexity of Many Cells in Arrangements of Planes and Related Problems.
The computation of certain numbers using a ruler and compass.
The Conic y = x2 in Moufang Planes
The connected components on the projective line over a ring.
The contributions of Hilbert and Dehn to non-archimedean geometries and their impact on the italian school
In this paper we investigate the contribution of Dehn to the development of non-Archimedean geometries. We will see that it is possible to construct some models of non-Archimedean geometries in order to prove the independence of the continuity axiom and we will study the interrelations between Archimedes’ axiom and Legendre’s theorems. Some of these interrelations were also studied by Bonola, who was one of the very few Italian scholars to appreciate Dehn’s work. We will see that, if Archimedes’...
The cross-ratio in Hjelmslev planes
The cross-ratio in Hjelmslev planes is defined. The cross-ratio in the Hjelmslev plane is independent of the choice of a coordinate system on a line.
The cyclic -clans with .
The cyclides of third order in pseudoisotropic space. II. (Die Zykliden 3. Ordnung im pseudoisotropen Raum. II.)