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).