Editing Compactification (mathematics) (section)

=== Spacetime compactification ===
[[Walter Benz]] and [[Isaak Yaglom]] have shown how [[stereographic projection]] onto a single-sheet [[hyperboloid]] can be used to provide a [[Motor variable#Compactification|compactification for split complex numbers]]. In fact, the hyperboloid is part of a [[quadric]] in real projective four-space. The method is similar to that used to provide a base manifold for [[group action (mathematics)|group action]] of the [[conformal group of spacetime]].<ref>15 parameter conformal group of spacetime described in {{Wikibooks-inline|Associative Composition Algebra/Homographies}}</ref>