Affiliation:
1. School of Science, Henan Institute of Technology , Xinxiang 453003 , Henan Province , P. R. China
Abstract
Abstract
Let
M
3
{M}^{3}
be a strictly almost cosymplectic three-manifold whose Ricci operator is weakly
ϕ
\phi
-invariant. In this article, it is proved that Ricci curvatures of
M
3
{M}^{3}
are invariant along the Reeb flow if and only if
M
3
{M}^{3}
is locally isometric to the Lie group
E
(
1
,
1
)
E\left(1,1)
of rigid motions of the Minkowski 2-space equipped with a left-invariant almost cosymplectic structure.
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