Let K be a field of characteristic 0 and let Mn(K) denote a K-algebra of n×n matrices
over K. It becomes a Lie algebra under Lie product [A, B] = AB − BA. We denote it
by gln(K). By sln(K) we denote a Lie subalgebra of gln(K) consisting of all matrices
A with tr(A) = 0. It is known that sln(K) is a simple Lie algebra (it has no nontrivial