Maximal Neutrino Mixing from Discrete Symmetry in Extra Dimensions
  I review the construction of a model for lepton masses based on the flavour symmetry group A4 x U(1) reproducing the so-called tri-bimaximal lepton mixing scheme, in eccelent agreement with current data. The model predicts a neutrino spectrum of normal hierarchy type, not far from degenerate. A testable relation between neutrino masses is obtained. I shortly discuss also general requirements for models based on spontaneously broken flavour symmetries, in order to get a maximal atmospheric mixing angle. 
Ferruccio Feruglio