On the planarity of the equilateral, isogonal pentagon.
A methodologically pure proof of a convex geometry problem.
Euclidean superpythagorean geometry.
Point-reflections in metric plane.
Affine super-Pythagorean geometry.
Orthogonality as single primitive notion for metric planes.
The elementary geometry of a triangular world with hexagonal circles.
Elementary versions of the Sylvester-Gallai theorem.
Hyperbolic geometry in terms of point-reflections or of line-orthogonality.
On the Pythagorean hull of Q.
The purpose of this paper is to prove that the Pythagorean hull of Q is the splitting field in R of a special set of rational polynomials.
An Axiomatics for Hyperbolic Projective-Metric Planes in Terms of Lines and Orthogonality
Hyperbolic projective-metric planes, first axiomatized by R. Lingenberg [7], are shown to be axiomatizable in terms of lines and orthogonality.
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