  We propose a realization of the so-called bimodal/schizophrenic model
proposed recently. We assume S4, the permutation group of four objects as
flavor symmetry giving tri-bimaximal lepton mixing at leading order. In these
models the second massive neutrino state is assumed quasi-Dirac and the
remaining neutrinos are Majorana states. In the case of inverse mass hierarchy,
the lower bound on the neutrinoless double beta decay parameter m_ee is about
two times that of the usual lower bound, within the range of sensitivity of the
next generation of experiments.
