On differentiable manifolds with $(\phi ,\,\psi)$-structures
On differentiable manifolds with $(\phi ,\,\psi)$-structures
Introduction.In a previous paper, υ we have defined for some odd dimensional manifolds two kinds of structures which we have called (φ, ξ, η) structure and (φ, ξ, η, ^-structure.The latter is a (φ, ζ, ^-structure with a positive definite Riemannian metric g which stands in a notable relation with …