Five dimensional almost para-cosymplectic manifolds with contact Ricci potential

There are studied in details 5-dimensional pseudo-Riemannian manifolds equipped with the structure analogous to the almost cosymplectic (almost coKaehler) structure. The curvature by assumption commutes with the structure affinor and all these manifolds are Walker spaces. There are obtained classifications for manifolds for contact Ricci potential, locally flat manifolds and described all connected, simply connected Lie groups admiting left-invariant structure. There are some other more general results.