This work is devoted to the study of Einstein equations with a special shape of the energy-momentum tensor. Our results continue Stepanov’s classification of Riemannian manifolds according to special properties of the energy-momentum tensor to Kähler manifolds. We show that in this case the number of classes reduces.
In this paper we study vector fields in Riemannian spaces, which satisfy , , We investigate the properties of these fields and the conditions of their coexistence with concircular vector fields. It is shown that in Riemannian spaces, noncollinear concircular and -vector fields cannot exist simultaneously. It was found that Riemannian spaces with -vector fields of constant length have constant scalar curvature. The conditions for the existence of -vector fields in symmetric spaces are given....
In this paper there are discussed the geodesic mappings which preserved the Einstein tensor. We proved that the tensor of concircular curvature is invariant under Einstein tensor-preserving geodesic mappings.
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