## Relations among low-dimensional simple Lie groups.(English)Zbl 1317.22005

The groups of $$n\times n$$ matrices $$\mathrm{SO}(n,{\mathbb R})$$, $$\mathrm{SU}(n,{\mathbb C})$$ and $$\mathrm{SO}(n,{\mathbb Q})$$ are the standard examples of the classical Lie groups over the real $${\mathbb R}$$, complex $${\mathbb C}$$ and quaternion fields $${\mathbb Q}$$. At low dimensions among them there exist some important isomorphisms or homomorphisms. Based on their Lie algebra structure the paper under review describes these relations by identifying the respective groups by their dimension and rank. Especially, the role of the real forms is emphasized and clarified. In fact, this article should be considered as a nice compendium to all books dealing with the structures of the Lie algebras, Lie groups and their representations.

### MSC:

 22E15 General properties and structure of real Lie groups 22E10 General properties and structure of complex Lie groups 17B20 Simple, semisimple, reductive (super)algebras