On 3-dimensional almost Einstein manifolds with circulant structures

Abstract

A 3-dimensional Riemannian manifold equipped with a tensor structure of type (1, 1), whose third poweris the identity, is considered. This structure and the metric have circulant matrices with respect to some basis, i.e.these structures are circulant. An associated manifold, whose metric is expressed by both structures, is studied. Threeclasses of such manifolds are considered. Two of them are determined by special properties of the curvature tensor of themanifold. The third class is composed by manifolds whose structure is parallel with respect to the Levi-Civita connectionof the metric. Some geometric characteristics of these manifolds are obtained. Examples of such manifolds are given.