Curvature properties of $4$-dimensional Riemannian manifolds with a circulant structure

Iva Dokuzova

We consider a $4$-dimensional Riemannian manifold $M$ equip\-ped with a circulant structure $q$, which is an isometry with respect to the metric $g$ and $q^{4}=\id$, $q^{2}\neq \pm…