Each Cartan matrix determines a unique semisimple complex Lie algebra via the Chevalley-Serre, sometimes called simply the "Serre relations." That is, if is a Cartan matrix then, up to isomorphism, there exists a unique semisimple complex Lie algebra (whose Cartan matrix is equivalent to ) such that is defined by a set of generators subject to the following Chevalley-Serre relations:
1.
2. and if
3.
4.
5.
6. .
Moreover, has rank and the 's generate a Cartan subalgebra. For proof, see Serre (1987).