Noncommutative cross-ratio and Schwarz derivative
arXiv:1905.01366
Abstract
We present here a theory of noncommutative cross-ratio, Schwarz derivative and their connections and relations to the operator cross-ratio. We apply the theory to "noncommutative elementary geometry" and relate it to noncommutative integrable systems. We also provide a noncommutative version of the celebrated "pentagramma mirificum".
24 pages, 3 figures. We add in the v.2 one figure and few references. We also had made some cosmetic language and phrase order changes