Hyperplane section of the complex Cayley plane as the homogeneous space
We prove that the exceptional complex Lie group has a transitive action on the hyperplane section of the complex Cayley plane . Although the result itself is not new, our proof is elementary and constructive. We use an explicit realization of the vector and spin actions of . Moreover, we identify the stabilizer of the -action as a parabolic subgroup (with Levi factor ) of the complex Lie group . In the real case we obtain an analogous realization of .