English

Cycles Cross Ratio: an Invitation

Metric Geometry 2023-05-09 v6 Complex Variables

Abstract

The paper introduces cycles cross ratio, which extends the classic cross ratio of four points to various settings: conformal geometry, Lie spheres geometry, etc. Just like its classic counterpart cycles cross ratio is a measure of anharmonicity between spheres with respect to inversion. It also provides a M\"obius invariant distance between spheres. Many further properties of cycles cross ratio awaiting their exploration. In abstract framework the new invariant can be considered in any projective space with a bilinear pairing.

Keywords

Cite

@article{arxiv.2105.05634,
  title  = {Cycles Cross Ratio: an Invitation},
  author = {Vladimir V. Kisil},
  journal= {arXiv preprint arXiv:2105.05634},
  year   = {2023}
}

Comments

10 pages, 3 PDF files in two figures, AMS-LaTeX; v2: Steiner power is linked to cross-ratio; v3: Jupyter notebook linked; v4: numerous improvements; v5: a couple of references is added; v6: minor corrections

R2 v1 2026-06-24T02:02:13.330Z