2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/62387Consider a bundle of circles passing through 0 in 4-dimensional space. It is said to be rectifiable if there is a germ of diffeomorphism at 0 that takes all circles from our bundle to straight lines. We will give a classification of all rectifiable bundles of circles containing sufficiently many circles in general position. This result is surprisingly different from those in dimensions 2 and 3(Khovanskii and Izadi) due to a connection with the quaternionic algebra.18 pagesDifferential GeometryMetric Geometry53A04; 11R52text