Tetrahedral Family Symmetry and the Neutrino Mixing Matrix

In a new application of the discrete non-Abelian symmetry A_4 using the canonical seesaw mechanism, a three-parameter form of the neutrino mass matrix is derived. It predicts the following mixing angles for neutrino oscillations: theta_{13}=0, sin^2 theta_{23}=1/2, and sin^2 theta_{12} close, but not exactly equal to 1/3, in one natural symmetry limit.