We propose a modification to the Lie algebra S-expansion method. The modification is carried out by imposing a condition on the S-expansion procedure, when the semigroup is given by a cyclic group of even order. The S-expanded algebras are called SH-expanded algebras where S=Z2n. The invariant tensors for SH-expanded algebras are calculated and the dual formulation of SH-expansion procedure is proposed. We consider the SH-expansion of the five-dimensional AdS algebra and its corresponding invariants tensors are found. Then a Chern-Simons Lagrangian invariant under the five-dimensional AdS algebra SH-expanded is constructed and its relationship to the general relativity is studied.
@article{arxiv.1605.00325,
title = {Einstein-Hilbert action with cosmological term from Chern-Simons gravity},
author = {N. L. González Albornoz and P. Salgado and G. Rubio and S. Salgado},
journal= {arXiv preprint arXiv:1605.00325},
year = {2016}
}