It is proved that for a non-Sasakian η-Einstein (κ, μ)-manifold M the following three conditions are equivalent: (a) M is flat and 3-dimensional, (b) M is Ricci-semisymmetric, and (c) M is ξ-Riccisemisymmetric. Then it is proved that an ξ-Ricci-semisymmetric (κ, μ)manifold M is either flat and 3-dimensional, or locally isometric to E × S(4), or an Einstein-Sasakian manifold. Mathematics Subject...

The aim of the present paper is to study a Bochner Ricci semi-symmetric quasi-Einstein Hermitian manifold (QEH)n, a Bochner Ricci semi-symmetric generalised quasi-Einstein Hermitian manifold G(QEH)n and a Bochner Ricci semisymmetric pseudo generalised quasi-Einstein Hermitian manifold P (GQEH)n.

In this paper we introduce the concept of (ε)-almost paracontact manifolds, and in particular, of (ε)-para Sasakian manifolds. Several examples are presented. Some typical identities for curvature tensor and Ricci tensor of (ε)-para Sasakian manifolds are obtained. We prove that if a semi-Riemannian manifold is one of flat, proper recurrent or proper Ricci-recurrent, then it can not admit an (ε...

The purpose of this study is to evaluate the curvature tensor and Ricci a P-Sasakian manifold with respect quarter-symmetric metric connection on tangent bundle TM. Certain results semisymmetric manifold, generalized recurrent manifolds, pseudo-symmetric manifolds TM are proved.

We investigate the properties of projective semisymmetric connections of a Riemannian manifold. Some interesting results with respect to the invariant of this semi-symmetric connection are given. Mathematics Subject Classification: 53C12

In the present study, we considered 3-dimensional generalized (κ, μ)-contact metric manifolds. We proved that a 3-dimensional generalized (κ, μ)-contact metric manifold is not locally φ-symmetric in the sense of Takahashi. However such a manifold is locally φ-symmetric provided that κ and μ are constants. Also it is shown that if a 3-dimensional generalized (κ, μ) -contact metric manifold is Ri...

In ([1]), T. Adati and K. Matsumoto defined para-Sasakian and special para-Sasakian manifolds which are considered as special cases of an almost paracontact manifold introduced by I. Sato and K. Matsumoto ([10]). In the same paper, the authors studied conformally symmetric para-Sasakian manifolds and they proved that an ndimensional (n>3) conformally symmetric para-Sasakian manifold is conforma...

TIn this article, the M-projective and Weyl curvature tensors on a normal paracontact metric manifold are discussed. For manifolds, pseudosymmetric cases investigated some interesting results obtained. We show that semisymmetric is of constant sectional curvature. also obtain an $\eta$-Einstein manifold. Finally, we support our topic with example.

For compact Kählerian manifolds, the holomorphic pseudosymmetry reduces to the local symmetry if additionally the scalar curvature is constant and the structure function is non-negative. Similarly, the holomorphic Ricci-pseudosymmetry reduces to the Ricci-symmetry under these additional assumptions. We construct examples of non-compact essentially holomorphically pseudosymmetric Kählerian manif...