I. Yavuz et U. Camci, RICCI COLLINEATIONS OF THE BIANCHI TYPE-II, TYPE-VIII, AND TYPE-IX SPACE-TIMES, General relativity and gravitation, 28(6), 1996, pp. 691-700
Ricci and contracted Ricci collineations of the Bianchi type II, VIII,
and IX space-times, associated with the vector fields of the form (i)
one component of xi(alpha)(x(b)) is different from zero and (ii) two
components of xi(alpha)(x(b)) are different from zero, for a, b = 1, 2
, 3, 4, are presented. In subcase (i.b), which is xi(alpha) = (0, xi(1
)(x(alpha)), 0, 0), some known solutions are found, and in subcase (i.
d), which is xi(alpha) = (0, 0, 0, xi(4)(x(alpha))) choosing S(t) = co
nst. x R(t), the Bianchi type II, VIII, and IX spacetime is reduced to
the Robertson-Walker metric.