Dynamical Models for Light Higgs Doublets in Supersymmetric Grand Unified Theories

We consider a supersymmetric hypercolor gauge theory with six flavors of quarks interacting strongly at the grand unification scale. This model solves the most serious problem -- doublet-triplet splitting in the grand unified theories. We also show that the dangerous dimension-five operators for nucleon decays are suppressed simultaneously, which makes our model yet more attractive.