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Mukut Mani Tripathi

Publications and source records attributed to Mukut Mani Tripathi.

At least 19 recordsLinked to original sources
arXiv2026

Casorati inequalities for Riemannian submersion along mixed distributions and their applications

This paper introduces Casorati inequalities for the normalised scalar curvature and normalised Casorati curvature of vertical and horizontal distributions for Riemannian submersions between Riemannian manifolds. We completely characterise the equality cases from both algebraic and geometric perspectives. As applications, we derive the corresponding inequalities for Riemannian submersions from real, complex, and generalised Sasakian space forms, including Sasakian, cosymplectic, Kenmotsu, and almost $C(α)$ space forms. We provide several examples to demonstrate the effectiveness and applicability of the results obtained.

math.DG↗
arXiv2026

B.-Y. Chen's inequalities for Riemannian submersion and their applications

In this paper, we introduce B.-Y. Chen inequalities for Riemannian submersions between Riemannian manifolds. We derive these inequalities for vertical, horizontal, and mixed distributions, establishing relationships between intrinsic invariants and extrinsic invariants. We also investigate the corresponding equality cases. As applications, the results are obtained for submersions whose total space is a real, complex, generalized Sasakian space form. Several examples are provided to illustrate both equality and strict inequality cases.

math.DG↗
arXiv2026

Newman--Penrose formalism in $3$-dimensional trans-Sasakian manifolds

We study $3$-dimensional trans-Sasakian manifolds using the Newman--Penrose formalism. In this framework, the geometry of the structure vector field is encoded by scalar spin coefficients: acceleration, shear, expansion, and twist. A central observation is that, in dimension $3$, the trans-Sasakian condition is equivalent to the characteristic vector field defining a shear-free geodesic congruence, or equivalently a conformal foliation by geodesics. Thus, the Newman--Penrose equations provide a direct scalar formulation of the conformal foliations studied by Baird and Wood in the theory of harmonic morphisms. Within this framework, we derive curvature and Laplacian identities for trans-Sasakian manifolds and their main subclasses, including formulae for the Ricci tensor, scalar curvature, Einstein condition, rough Laplacian, divergence and harmonicity of the characteristic vector field, together with several illustrative examples. As an application, we consider trans-Sasakian structures compatible with fixed homogeneous metrics of type ${\Bbb E}(κ,τ)$. We prove a rigidity result: in the non-space-form cases, the Newman--Penrose equations force the characteristic vector field to be vertical. Hence, for $τ\neq0$ and $κ\neq4τ^2$, every compatible trans-Sasakian structure is the canonical vertical $α$-Sasakian structure, while for $τ=0$ and $κ\neq0$, it is vertical and cosymplectic. In particular, these non-space-form homogeneous metrics admit no proper compatible trans-Sasakian structures.

math.DG↗
arXiv2019

Geometry of lightlike hypersurfaces of a statistical manifold

Lightlike hypersurfaces of a statistical manifold are studied. It is shown that a lightlike hypersurface of a statistical manifold is not a statistical manifold with respect to the induced connections, but the screen distribution has a canonical statistical structure. Some relations between induced geometric objects with respect to dual connections in a lightlike hypersurface of a statistical manifold are obtained. An example is presented. Induced Ricci tensors for lightlike hypersurface of a statistical manifold are computed.

math.DG↗
arXiv2018

Certain results on almost contact pseudo-metric manifolds

We study the geometry of almost contact pseudo-metric manifolds in terms of tensor fields $h:=\frac{1}{2}£_ξφ$ and $\ell := R(\cdot,ξ)ξ$, emphasizing analogies and differences with respect to the contact metric case. Certain identities involving $ξ$-sectional curvatures are obtained. We establish necessary and sufficient condition for a nondegenerate almost $CR$ structure $(\mathcal{H}(M), J, θ)$ corresponding to almost contact pseudo-metric manifold $M$ to be $CR$ manifold. Finally, we prove that a contact pseudo-metric manifold $(M,φ,ξ,η,g)$ is Sasakian if and only if the corresponding nondegenerate almost $CR$ structure $(\mathcal{H}(M), J)$ is integrable and $J$ is parallel along $ξ$ with respect to the Bott partial connection.

math.DG↗
arXiv2016

Inequalities for algebraic Casorati curvatures and their applications

The notion of different kind of algebraic Casorati curvatures are introduced. Some results expressing basic Casorati inequalities for algebraic Casorati curvatures are presented. Equality cases are also discussed. As a simple application, basic Casorati inequalities for different $δ$-Casorati curvatures for Riemannian submanifolds are presented. Further applying these results, Casorati inequalities for Riemannian submanifolds of real space forms are obtained. Finally, some problems are presented for further studies.

math.DG↗
arXiv2014

Lightlike hypersurfaces of an $(ε)$-para Sasakian manifold

In this paper, we initiate the study of lightlike hypersurfaces of an $(ε)$-almost paracontact metric manifold which are tangent to the structure vector field. In particular, we give definitions of invariant lightlike hypersurfaces and screen semi-invariant lightlike hypersurfaces, and give some examples. Integrability conditions for the distributions involved in the screen semi-invariant lightlike hypersurface are investigated when the ambient manifold is an $(ε)$-para Sasakian manifold.

math.DG↗
arXiv2012

Semi-parallelism of normal Jacobi operator for Hopf hypersurfaces in complex two-plane Grassmannians

It is proved the non-existence of Hopf hypersurfaces in $G_{2}({\Bbb C}^{m+2})$, $m \geq 3$, whose normal Jacobi operator is semi-parallel, if the principal curvature of the Reeb vector field is non-vanishing and the component of the Reeb vector field in the maximal quaternionic subbundle ${\frak D}$ or its orthogonal complement ${\frak D}^{\bot}$ is invariant by the shape operator.

math.DG↗
arXiv2012

A note on trans-Sasakian manifolds

In this paper, we obtain some sufficient conditions for a 3-dimensional compact trans-Sasakian manifold of type $(α,β)$ to be homothetic to a Sasakian manifold. A characterization of a 3-dimensional cosymplectic manifold is also obtained.

math.DG↗
arXiv2012

Einstein like $(\varepsilon)$-para Sasakian manifolds

Einstein like $(\varepsilon)$-para Sasakian manifolds are introduced. For an $(\varepsilon) $-para Sasakian manifold to be Einstein like, a necessary and sufficient condition in terms of its curvature tensor is obtained. The scalar curvature of an Einstein like $(\varepsilon) $-para Sasakian manifold is obtained and it is shown that the scalar curvature in this case must satisfy certain differential equation. A necessary and sufficient condition for an $(\varepsilon) $-almost paracontact metric hypersurface of an indefinite locally Riemannian product manifold to be $(\varepsilon) $-para Sasakian is obtained and it is proved that the $(\varepsilon) $-para Sasakian hypersurface of an indefinite locally Riemannian product manifold of almost constant curvature is always Einstein like.

math.DG↗
arXiv2012

On $(N(k),ξ)$-semi-Riemannian manifolds: Pseudosymmetries

Definition of $({\cal T}_{a},{\cal T}_{b})$-pseudosymmetric semi-Riemannian manifold is given. $({\cal T}_{a},{\cal T}_{b})$-pseudosy mmetric $(N(k),ξ)$-semi-Riemannian manifolds are classified. Some results for ${\cal T}_{a}$-pseudosymmetric $(N(k),ξ)$-semi-Riemannian manifolds are obtained. $({\cal T}_{a},{\cal T}_{b},S^{\ell})$-pseudosymmetric semi-Riemannian manifolds are defined. $({\cal T}_{a},{\cal T}_{b},S^{\ell})$-pseudosymmetric $(N(k),ξ)$-semi-Riemannian manifolds are classified. Some results for $(R,{\cal T}_{a},S^{\ell})$-pseudosymmetric $(N(k),ξ)$-semi-Riemannian manifolds are obtained. In particular, some results for $(R,{\cal T}_{a},S)$-pseudosymmetric $(N(k),ξ)$-semi-Riemannian manifolds are also obtained. After that, the definition of $({\cal T}_{a},S_{{\cal T}_{b}})$-pseudosymmetric semi-Riemannian manifold is given. $({\cal T}_{a},S_{{\cal T}_{b}})$-pseudosymmetric $(N(k),ξ)$-semi-Riemannian manifolds are classified. It is proved that a $(R,S_{{\cal T}_{a}})$-pseudosymmetric $(N(k),ξ)$-semi-Riemannian manifold is either Einstein or $L=k$ under an algebraic condition. Some results for $({\cal T}_{a},S)$-pseudosymmetric $(N(k),ξ)$-semi-Riemannian manifolds are also obtained. In last, $({\cal T}_{a},S_{{\cal T}_{b}},S^{\ell})$-pseudosymmetric semi-Riemannian manifolds are defined and $({\cal T}_{a},S_{{\cal T}_{b}},S^{\ell})$ -pseudosymmetric $(N(k),ξ)$-semi-Riemannian manifolds are classified.

math.DG↗
arXiv2012

On $(N(k),ξ)$-semi-Riemannian manifolds: Semisymmetries

$(N(k),ξ)$-semi-Riemannian manifolds are defined. Examples and properties of $(N(k),ξ)$-semi-Riemannian manifolds are given. Some relations involving ${\cal T}_{a}$-curvature tensor in $(N(k),ξ)$-semi-Riemannian manifolds are proved. $ξ$-${\cal T}_{a}$-flat $(N(k),ξ)$-semi-Riemannian manifolds are defined. It is proved that if $M$ is an $n$-dimensional $ξ$-${\cal T}_{a}$-flat $(N(k),ξ)$-semi-Riemannian manifold, then it is $η$-Einstein under an algebraic condition. We prove that a semi-Riemannian manifold, which is $T$-recurrent or $T$-symmetric, is always $T$-semisymmetric, where $T$ is any tensor of type $(1,3)$. $({\cal T}_{a}, {\cal T}_{b}) $-semisymmetric semi-Riemannian manifold is defined and studied. The results for ${\cal T}_{a}$-semisymmetric, ${\cal T}_{a}$-symmetric, ${\cal T}_{a}$-recurrent $(N(k),ξ)$-semi-Riemannian manifolds are obtained. The definition of $({\cal T}_{a},S_{{\cal T}_{b}})$-semisymmetric semi-Riemannian manifold is given. $({\cal T}_{a},S_{{\cal T}_{b}})$-semisymmetric $(N(k),ξ)$-semi-Riemannian manifolds are classified. Some results for ${\cal T}_{a}$-Ricci-semisymmetric $(N(k),ξ)$-semi-Riemannian manifolds are obtained.

math.DG↗
arXiv2012

Generalized (κ,μ)-space forms

Generalized (κ,μ)-space forms are introduced and studied. We examine in depth the contact metric case and present examples for all possible dimensions. We also analyse the trans-Sasakian case.

math.DG↗
arXiv2009

On $(\varepsilon)$-para Sasakian 3-manifolds

In this paper we study the 3-dimensional $(\varepsilon) $-para Sasakian manifolds. We obtain an necessary and sufficient condition for an $(\varepsilon ) $-para Sasakian 3 -manifold to be an indefinite space form. We show that a Ricci-semi-symmetric $(\varepsilon) $-para Sasakian 3 -manifold is an indefinite space form. We investigate the necessary and sufficient condition for an $(\varepsilon) $-para Sasakian 3 -manifold to be locally $φ$-symmetric. It is proved that in an $ (\varepsilon) $-para Sasakian 3-manifold with $η$ -parallel Ricci tensor the scalar curvature is constant. It is also shown that every $(\varepsilon) $-para Sasakian 3-manifolds is pseudosymmetric in the sense of R. Deszcz.

math.DG↗