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2019, Mathematics and Statistics
https://doi.org/10.13189/ms.2019.070408…
4 pages
1 file
The Fundamental Theorem of Riemannian geometry states that on a Riemannian manifold there exist a unique symmetric connection compatible with the metric tensor. There are numerous examples of connections that even locally do not admit any compatible met-rics. A very important class of symmetric connections in the tangent bundle of a certain manifolds (afinnely flat) are the ones for which the curvature tensor vanishes. Those connections are locally metric. S.S. Chern conjectured that the Euler characteristic of an affinely flat manifold is zero. A possible proof of this long outstanding conjecture of S.S. Chern would be by verifying that the space of locally metric connections is path connected. In order to do so one needs to have practical criteria for the metrizability of a connection. In this paper we give necessary and sufficient conditions for a connection in a plane bundle above a surface to be locally metric. These conditions are easy to be verified using any local frame. Also, as a global result we give a necessary condition for two connections to be metric equivalent in terms of their Euler class.
2021
We extend the well-known formula for the Euler class of a real oriented even-dimensional vector bundle in terms of the curvature of a metric connection to the case of a general linear connection provided a metric is present. We rewrite the classical Gauss-Bonnet theorem in dimension two in light of this formula. We also discuss a potential application to a conjecture of Chern, and make a brief digression to discuss m-quasi-Einstein manifolds.
2019
Let E → M be an arbitrary vector bundle of rank k over a Riemannian manifold M equipped with a fiber metric and a compatible connection DE . R. Albuquerque constructed a general class of (twoweights) spherically symmetric metrics on E. In this paper, we give a characterization of locally symmetric spherically symmetric metrics on E in the case when DE is flat. We study also the Einstein property on E proving, among other results, that if k ≥ 2 and the base manifold is Einstein with positive constant scalar curvature, then there is a 1parameter family of Einstein spherically symmetric metrics on E, which are not Ricci-flat. Introduction and main results In the framework of Riemannian geometry, many special kinds of vector bundles have been considered and extensively studied, such as the cotangent bundle or the tangent bundle the literature of whose is very rich. Indeed, a wide range of interesting works have been published on the geometry of tangent bundles endowed with special types...
Facta Universitatis, Series: Mathematics and Informatics, 2021
The differential geometry of the tangent bundle is an effective domain of differential geometry which reveals many new problems in the study of modern differential geometry. The generalization of connection on any manifold to its tangent bundle is an application of differential geometry. Recently a new type of semi-symmetric non-metric connection on a Riemannian manifold has been studied and a relationship between Levi-Civita connection and semi-symmetric non-metric connection has been established. The various properties of a Riemannian manifold with relation to such connection have also been discussed. The present paper aims to study the tangent bundle of a new type of semi-symmetric non-metric connection on a Riemannian manifold. The necessary and sufficient conditions for projectively invariant curvature tensors corresponding to such connection are proved and show many basic results on the Riemannian manifold in the tangent bundle. Furthermore, the properties of group manifolds of the Riemannian manifolds with respect to the semi-symmetric non-metric connection in the tangent bundle have been studied. Moreover, theorems on the symmetry property of Ricci tensor and Ricci soliton in the tangent bundle are established.
2014
The main purpose of this paper is to study the conn ections on vector bundle and apply connections to prove the Bianchi identity and Christoffel symbols.
Journal of Geometry, 2018
Let M be an n−dimensional differentiable manifold equipped with a torsion-free linear connection ∇ and T * M its cotangent bundle. The present paper aims to study a metric connection ∇ with nonvanishing torsion on T * M with modified Riemannian extension g ∇,c. First, we give a characterization of fibre-preserving projective vector fields on (T * M, g ∇,c) with respect to the metric connection ∇. Secondly, we study conditions for (T * M, g ∇,c) to be semi-symmetric, Ricci semi-symmetric, Z semi-symmetric or locally conharmonically flat with respect to the metric connection ∇. Finally, we present some results concerning the Schouten-Van Kampen connection associated to the Levi-Civita connection ∇ of the modified Riemannian extension g ∇,c. Mathematics subject classification 2010. 53C07, 53C35, 53A45.
The main purpose of this paper is to study the connections on vector bundle and apply connections to prove the Bianchi identity and Christoffel symbols.
Mathematical Proceedings of the Cambridge Philosophical Society, 2005
The concept of generalised (in the sense of Colombeau) connection on a principal fibre bundle is introduced. This definition is then used to extend results concerning the geometry of principal fibre bundles to those that only have a generalised connection. Some applications to singular solutions of Yang-Mills theory are given.
Rendiconti del Circolo Matematico di Palermo
We give coordinate formula and geometric description of the curvature of the tensor product connection of linear connections on vector bundles with the same base manifold. We define the covariant differential of geometric fields of certain types with respect to a pair of a linear connection on a vector bundle and a linear symmetric connection on the base manifold. We prove the generalized Bianchi identity for linear connections and we prove that the antisymmetrization of the second order covariant differential is expressed via the curvature tensors of both connections.
International Journal of Pure and Apllied Mathematics, 2016
We study the existence and the behavior of a linear connection from a curvature given in a n-dimensional riemannian manifold M. For a polynomial section of the dual space of T M on R n , in particular, we find that there is a polynomial linear connection on R n. We prove that if the nullity space of the Ricci tensor is equal to that of the curvature, then the Ricci tensor and the curvature coincide.
In this paper we define a class of torsion-free connections on the total space of the (co-)tangent bundle over a base-manifold with a connection and for which tangent spaces to the fibers are parallel. Each tangent space to a fiber is flat for these connections and the canonical projection from the (co-)tangent bundle to the base manifold is totally geodesic. In particular cases the connection is metric with signature (n,n) or symplectic and admits a single parallel totally isotropic tangent n-plane.
European Journal of Pure and Applied Mathematics, 2011
In this study, we consider a manifold equipped with semi symmetric metric connection whose the torsion tensor satisfies a special condition. We investigate some properties of the Ricci tensor and the curvature tensor of this manifold. We obtain a necessary and sufficient condition for the mixed generalized quasi-constant curvature of this manifold. Finally, we prove that if the manifold mentioned above is conformally flat, then it is a mixed generalized quasi-Einstein manifold and we prove that if the sectional curvature of a Riemannian manifold with a semi symmetric metric connection whose the special torsion tensor is independent from orientation chosen, then this manifold is of a mixed generalized quasi constant curvature.
Kyungpook mathematical journal, 2016
In this paper we study some properties of submanifolds of a Riemannian manifold equipped with a generalized connection ▽. We also consider almost Hermitian manifolds that admits a special case of this generalized connection and derive some results about the behavior of this manifolds.
2016
Abstract: We study the existence and the behavior of a linear connection from a curvature given in a n-dimensional riemannian manifold M . For a polynomial section of the dual space of T M on R n , in particular, we find that there is a polynomial linear connection on R n . We prove that if the nullity space of the Ricci tensor is equal to that of the curvature, then the Ricci tensor and the curvature coincide.
arXiv (Cornell University), 2011
A Riemannian manifold M with an integrable almost product structure P is called a Riemannian product manifold. Our investigations are on the manifolds (M, P, g) of the largest class of Riemannian product manifolds, which is closed with respect to the group of conformal transformations of the metric g. This class is an analogue of the class of locally conformal Kähler manifolds in almost Hermitian geometry. In the present paper we study a natural connection D on (M, P, g) (i.e. DP = Dg = 0). We find necessary and sufficient conditions the curvature tensor of D to have properties similar to the Kähler tensor in Hermitian geometry. We pay attention to the case when D has a parallel torsion. We establish that the Weyl tensors for the connection D and the Levi-Civita connection coincide as well as the invariance of the curvature tensor of D with respect to the usual conformal transformation. We consider the case when D is a flat connection. We construct an example of the considered manifold by a Lie group where D is a flat connection with non-parallel torsion.
Considering two natural principal bundle structures on T 2 M , one prove that a Finsler metric defines flat connections in these bundles.
Journal of Geometry and Physics, 2021
We consider a family of α-connections defined by a pair of generalized dual quasistatistical connections (∇,∇ *) on the generalized tangent bundle (T M ⊕ T * M,ȟ) and determine their curvature, Ricci curvature and scalar curvature. Moreover, we provide the necessary and sufficient condition for∇ * to be an equiaffine connection and we prove that if h is symmetric and ∇h = 0, then (T M ⊕ T * M,ȟ,∇ (α) ,∇ (−α)) is a conjugate Ricci-symmetric manifold. Also, we characterize the integrability of a generalized almost product, of a generalized almost complex and of a generalized metallic structure w.r.t. the bracket defined by the α-connection. Finally we study α-connections defined by the twin metric of a pseudo-Riemannian manifold, (M, g), with a non-degenerate g-symmetric (1, 1)-tensor field J such that d ∇ J = 0, where ∇ is the Levi-Civita connection of g.
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