A method to find generators of a semi-simple Lie group via the topology of its flag manifolds

In this paper we continue to develop the topological method started in Santos-San Martin \cite{ariasm} to get semigroup generators of semi-simple Lie groups. Consider a subset $\Gamma \subset G$ that contains a semi-simple subgroup $G_{1}$ of $G$. Then $\Gamma $ generates $G$ if $\mathrm{Ad}\left( \Gamma \right) $ generates a Zariski dense subgroup of the algebraic group $\mathrm{Ad}\left( G\right) $. The proof is reduced to check that some specific closed orbits of $G_{1}$ in the flag manifolds of $G$ are not trivial in the sense of algebraic topology. Here, we consider three different cases of semi-simple Lie groups $G$ and subgroups $G_{1}\subset G$.