  We study Majorana neutrino mass matrices that have two texture zeros, or two
cofactor zeros, or one texture zero and one cofactor zero. The two
texture/cofactor zero conditions give four constraints, which in conjunction
with the five measured oscillation parameters completely determine the nine
independent real parameters of the neutrino mass matrix. We also study the
implications that future measurements of neutrinoless double beta decay and the
Dirac CP phase will have on these cases.
