Von Staudt's theorem revisited

Abstract

We establish a version of von Staudt's theorem on mappings which preserve harmonic quadruples for projective lines over (not necessarily commutative) rings with "sufficiently many" units, in particular 2 has to be a unit.

More typos corrected

References in corpus (5)

• Projective Representations I. Projective lines over rings
• The Connected Components of the Projective Line over a Ring
• On distant-isomorphisms of projective lines
• Jordan homomorphisms and harmonic mappings
• The Dual of a Chain Geometry