A Lie algebra g is nilpotent if the k-th element D_k(g) in the low central series for g is 0 for some k >= 0.

Query(Alg, "Nilpotent") returns true if Alg is a nilpotent Lie algebra and false otherwise.  If the algebra is unspecified, then Query is applied to the current algebra.

Query(S, "Nilpotent") returns true if the subalgebra S is a nilpotent Lie algebra and false otherwise.

The command Query is part of the DifferentialGeometry:-LieAlgebras package.  It can be used in the form Query(...) only after executing the commands with(DifferentialGeometry) and with(LieAlgebras), but can always be used by executing DifferentialGeometry:-LieAlgebras:-Query(...).