The link is about set theory, but others may find this interesting which discusses division algebras https://nigelvr.github.io/post-4.html https://nigelvr.githu

The link is about set theory, but others may find this interesting which discusses division algebras https://nigelvr.github.io/post-4.html https://nigelvr.github.io/post-4.html Basically C comes up in the chain R \subset C \subset H (quaternions) \subset O (octonions) by the so-called Cayley-Dickson construction. There is a lot of structure.