Cross ratios and the Ptolemaean inequality in boundaries of symmetric spaces of rank 1

Abstract

We use generalised cross--ratios to prove the Ptolemaean inequality and the Theorem of Ptolemaeus in the setting of the boundary of symmetric Riemannian spaces of rank 1 and of negative curvature.

References in corpus (2)

• Moebius structures and Ptolemy spaces: boundary at infinity of complex hyperbolic spaces
• Complex cross--ratios and the Ptolemaean inequality