J C Ndogmo 2004 J. Phys. A: Math. Gen. 37 5635 doi:10.1088/0305-4470/37/21/009
J C Ndogmo
Show affiliationsWe show that any semi-direct sum L of Lie algebras with Levi factor S must be perfect if the representation associated with it does not possess a copy of the trivial representation. As a consequence, all invariant functions of L must be Casimir operators. When
, the number of invariants is given for all possible dimensions of L. Replacing the traditional method of solving the system of determining PDEs by the equivalent problem of solving a system of total differential equations, the invariants are found for all dimensions of the radical up to 5. An analysis of the results obtained is made, and this leads to a theorem on invariants of Lie algebras depending only on the elements of certain subalgebras.
22E60 Lie algebras of Lie groups (For the algebraic theory of Lie algebras, see 17Bxx)
Issue 21 (28 May 2004)
Received 13 February 2004, in final form 2 April 2004
Published 12 May 2004
J C Ndogmo 2004 J. Phys. A: Math. Gen. 37 5635
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