Metric characterizations of hyperbolic and Euclidean spaces
Metric rigidity of crystallographic groups.
Mini-programs for hidden lines on a surface
Many programs for the hidden lines on a surface are known [1] but these programs are long and need a large memory of the computer. In this paper we show algorithms and the corresponding mini-program in BASIC which can be implemented on minicomputers with plotters or plotting displays. We map the surface in the parallel or central projections.
Neue Fassung einer Verallgemeinerung des Satzes von Napoleon.
Note sur l'expression de la distance entre quelques points remarquables d'un triangle ABC
O úhlech nesouměřitelných
On a general principle in geometry that leads to functional equations.
On Brocard points in the isotropic plane.
On distance preserving transformations of lines in Euclidean three-space.
On the bisectors of weakly separable sets.
On the Contact Dimension of Graphs.
On the foundation of geometry.
On the Group of Transformations of Constructible Euclidean Planes with Preserve a Single Distance.
On the planarity of the equilateral, isogonal pentagon.
On the plane geometry with generalized absolute value metric.
Parabeln mit gemeinsamen isotropem Krümmungskreis.
"Paradoxe" Zerlegung Euklidischer Räume.
Parallelbeleuchtung konvexer Körper mit glatten Rändern
Placing and moving spheres in the gaps of a cylinder packing.
Point-reflections in metric plane.