Lepton residual symmetries

Some aspects concerning the flavor symmetry were studied. Two
approaches are discussed to deal with flavor symmetry. The desired
lepton mixing matrix determines the flavor symmetry group up to a certain
representation.
The dependence of the lepton mixing matrix on the representation of
the symmetry group accounts for the differences between models used the
same symmetry group.
We discuss the connection between the two approaches to fix flavor
assignments and alignments of flavor vacuum.
Another approach is called bottom- up or the residual symmetry
approach, at which the lepton mass matrices are considered to have remnant
symmetry of breaking discrete group. The goal of this approach is to get this
discrete group.