Abstract
Three neutrino vacuum transitions and oscillations in the general case were considered and
expressions for neutrino wave functions in three cases: with CP violation, without CP violation
and the case when direct e $ transitions are absent,i.e., at (13) = 0 (some
works indicate on this possibility) were obtained. There were also computed transition probabilities
for the case of CP conservation and for absence of direct e $ transitions, i.e.
(13) = 0. It was shown that the probability Pe!e (t) at e $ e neutrino transitions is
definitely positive value if m2
13 = m2
12 + m2
23.