  It is shown that various versions of the neutrino mixing hypothesis are in a
contradiction with generally accepted facts and principles.There is also
presented the possible alternative formulation of the neutrino oscillation
theory and it is shown under what conditions this theory reproduces the known
oscillation probability formula. In our approach (flavor) neutrinos are Dirac
particles. In the case of Majorana neutrinos, or the nonrelativistic neutrinos
(i.e. relic neutrinos) the problem could be more complicated.
