Vertical-horizontal symmetric minimal grand-unification

With the motivation that the traditional generation structure is a fundamental property of nature, namely that it perfectly survives at ultra-high energies beyond the unification mass, we are led to consider semi-simple grand unified theories. A discrete vertical-horizontal symmetry must then be invoked to ensure a single gauge coupling constant. This in turn is shown to provide a natural origin for fixing the fermion representations and especially the total number of flavors. Within a multigeneration generalization of the Georgi-Glashow SU(5) theory, we predict five ordinary mass fermion families.