Title: Riemannian almost product manifolds generated by a circulant structure,
Abstract: A 4-dimensional Riemannian manifold equipped with a circulant structure,
which is an isometry with respect to the metric and its fourth power is the
identity, is considered. The almost product manifold associated with the
considered manifold is studied. The relation between the covariant derivatives
of the almost product structure and the circulant structure is obtained. The
conditions for the covariant derivative of the circulant structure, which imply
that an almost product manifold belongs to each of the basic classes of the
Staikova-Gribachev classification, are given.