2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/57258For sp(n+2) and each exceptional Lie algebra a realization of depth 2 preserving the spaces spanned by a contact one-form and a bilinear form is given. For e_7 and e_6 a realization of depth 1 preserving a lightcone and the space spanned by a bilinear form is also presented. This makes the origin of the exceptions clear.Mathematical Physicstext