Triplicated Trinification

Gauge-coupling unification is just as successful in the standard model with six Higgs doublets as it is in the minimal supersymmetric standard model. However, the gauge couplings unify at 10^14 GeV, which yields rapid proton decay in the SU(5) model. I propose that the grand-unified gauge group is instead SU(3)_c x SU(3)_L x SU(3)_R, in which baryon number is conserved by the gauge interactions.