On the Reduction of CP Violation Phases
  We describe a method that is used to reduce, significantly, the number of CP violating complex phases in the Yukawa parameters. With this Reduction of Complex Phases (RCP) we obtain only one CP violating complex phase in the case where the neutrinos have an (effective) $3\times 3$ Majorana mass matrix. For the See Saw extension of the SM with three righthanded neutrinos, and in connection with CP violation in leptogenis, we reduce the usual 6 complex phases to only 2. 
J.I. Silva-Marcos