Tangents of conics in Hjelmslev planes over a local ring of even characteristic
The classification of compact right chain rings.
The connected components on the projective line over a ring.
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 geometrical Barbilian's work from a modern point of view.
Twin “Fano-snowflakes” over the smallest ring of ternions.