共查询到20条相似文献,搜索用时 15 毫秒
1.
Bayram Sahin 《Geometriae Dedicata》2006,117(1):195-202
In this paper, we show that there are no warped product semi-slant submanifolds of Kaehler manifolds. Contrary to this result,we
provide an elementary example of a CR-warped product submanifold of a Kaehler manifold 相似文献
2.
本文给出了Sasakian流形中反不变极小子流形是稳定或不稳定的一个充分条件. 相似文献
3.
Mehmet Ateken 《数学物理学报(B辑英文版)》2010,30(1):215-224
In this article, the geometry of the slant submanifolds of a Riemannian product manifold is studied. Some necessary and sufficient conditions on slant, bi-slant and semi-slant submanifolds are given. We research fundamental properties of the distributions which are involved in definitions of semi- and bi-slant submanifolds in a Riemannian product manifold. 相似文献
4.
本文定义并讨论了近乎Sasakian流形的CR子流形,得到了关开这类子流形的微分几何方面的一些有意义的结果。 相似文献
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6.
SkewCRSubmanifoldsofaSasakianManifoldLiuXimin(刘西民)(DepartmentofMathematics,NankaiUniversity,Tianjin,300071)LiangXiquan(梁希泉)(I... 相似文献
7.
In this paper, we obtain some sharp inequalities between the Ricci cur- vature and the squared mean curvature for bi-slant and semi-slant submanifolds in Kenmotsu space forms. Estimates of the scalar curvature and the k-Ricci curvature, in terms of the squared mean curvature, are also proved respectively. 相似文献
8.
Recently, B.-Y. Chen studied warped products which are CR-submanifolds in Kaehler manifolds and established general sharp inequalities for CR-warped products in Kaehler manifolds. In the present paper, we obtain a sharp inequality for the squared norm of the second fundamental form (an extrinsic invariant) in terms of the warping function for contact CR-warped products isometrically immersed in Sasakian manifolds. The equality case is considered. Also, the minimum codimension of a contact CR-warped product in an odd-dimensional sphere is determined. 相似文献
9.
Yueshan XIONG 《Frontiers of Mathematics in China》2015,10(2):395
The homotopy connectedness theorem for invariant immersions in Sasakian manifolds with nonnegative transversal q-bisectional curvature is proved. Some Barth-Lefschetz type theorems for minimal submanifolds and (k, ?)-saddle submanifolds in Sasakian manifolds with positive transversal q-Ricci curvature are proved by using the weak (?-)asymptotic index. As a corollary, the Frankel type theorem is proved. 相似文献
10.
Recently, B.-Y. Chen studied warped products which are CR-submanifolds in Kaehler manifolds and established general sharp inequalities for CR-warped products in Kaehler manifolds. Afterwards, I. Hasegawa and the present author obtained a sharp inequality for the squared norm of the second fundamental form (an extrinsic invariant) in terms of the warping function for contact CR-warped products isometrically immersed in Sasakian manifolds. In this paper, we improve the above inequality for contact CR-warped products in Sasakian space forms. Some applications are derived. A classification of contact CR-warped products in spheres, which satisfy the equality case, identically, is given.Mathematics Subject Classifications (2000). 53C40, 53C25. 相似文献
11.
Alfonso Carriazo Luis M. Ferná ndez 《Proceedings of the American Mathematical Society》2004,132(11):3327-3336
In this paper we present an interesting relationship between graph theory and differential geometry by defining submanifolds of almost Hermitian manifolds associated with certain kinds of graphs. We show some results about the possibility of a graph being associated with a submanifold and we use them to characterize CR-submanifolds by means of trees. Finally, we characterize submanifolds associated with graphs in a four-dimensional almost Hermitian manifold.
12.
§1. PreliminariesLetMbea(2n+1)-dimensionalcontactmetricmanifoldwithstructuretensors(Φ-,ξ-,η-,g).ThentheysatisfyΦ-ξ-=0,η-(ξ-)=1,Φ-2=-I+η-ξ-,η-(X)=g(X,ξ-), g(Φ-X,Φ-Y)=g(X,Y)-η-(X)η-(Y),g(X,Φ-Y)=dη-(X,Y)(1.1)ForanyvectorfieldsXandY… 相似文献
13.
SUN He-jun WU Bao-qiang.Academy of Mathematics System Sciences Chinese Academy of Sciences Beijing China .Department of Mathematics Xuzhou Normal University Xuzhou China 《数学季刊》2004,19(1):6-15
We first establish a integral inequality for compact maximal space-like subman ifolds in pseudo-Riemannian manifolds Np(n+p). Then, we investigate compact space-like sub manifolds and hupersurfaces with parallel second fundamental form in Np(n+p) and some other ambient spaces. We obtain some distribution theorems for the square norm of the second fundamental form. 相似文献
14.
关于局部对称伪黎曼流形中的2-调和类空子流形 总被引:1,自引:0,他引:1
研究局部对称伪黎曼流形中的2-调和类空子流形,得到了这类子流形成为极大的Pinching现象及推广的J.Simons型积分不等式. 相似文献
15.
Elisabetta Barletta 《Annals of Global Analysis and Geometry》2002,22(2):99-118
We study CR submanifolds M in a Hopf manifold (C
H
N
(), J
0, g
0) with the Boothby metric g
0,of maximal CR dimension. Any such M is a CR manifold ofhypersurface type, although embedded in higher codimension, and itsanti-invariant distribution H(M) is spanned by a unit vectorfield U. We classify the CR submanifolds M for which = –J
0
Uis parallel in the normal bundle under assumptions on thespectrum of the Weingarten operator a
. We show that (1) ifa
(U) = (1/2)A (where A is the anti-Lee vector) andM fibres in tori over a CR submanifold of the complex projectivespace, then M lies on the (total space of the) pullback of the Hopf fibration via S C
P
N – 1, for some geodesic hypersphere S, and (2) if a
(U)= 0 and Spec(a
) = {0, c}, for some c R {0}, then M is locally a Riemannian product of totally geodesicsubmanifolds. 相似文献
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By using the methods introduced by Chen[Chen Bang-yen,A series of Ka¨hlerian invarianrts and their applications to Khlerian geometry,Beitrge Algebra Geom,2001,42(1):165-178],we establish some inequalities for invariant submanifolds in a Sasakian space form involving totally real sectional curvature and the scalar curvature.Moreover,we consider the case of equalities. 相似文献
18.
本文研究了殆Kaehler流形中CR子流形的上同调、CR子波形的分布D及其正交补D⊥的维数大于1的时候,近Kaehler流形中每个全脐非平凡的CR子流形一定是全测地的。最后得到:如果M^~是具有H^~B>0的近Kaehler流形,那么M^~不允许有混合叶层非凡的CR子流形。 相似文献
19.
We give a procedure to ‘average’ canonically C1-close Legendrian submanifolds of contact manifolds. As a corollary we obtain that, whenever a compact group action leaves
a Legendrian submanifold almost invariant, there is an invariant Legendrian submanifold nearby.
Mathematics Subject Classification (2000): 53D10. 相似文献
20.
A contact manifold M can be defined as a quotient of a symplectic manifold X by a proper, free action of \(\mathbb{R}\), with the symplectic form homogeneous of degree 2. If X is also Kähler, and its metric is homogeneous of degree 2, M is called Sasakian. A Sasakian manifold is realized naturally as a level set of a Kähler potential on a complex manifold, hence it is equipped with a pseudoconvex CR-structure. We show that any Sasakian manifold M is CR-diffeomorphic to an S 1-bundle of unit vectors in a positive line bundle on a projective Kähler orbifold. This induces an embedding of M into an algebraic cone C. We show that this embedding is uniquely defined by the CR-structure. Additionally, we classify the Sasakian metrics on an odd-dimensional sphere equipped with a standard CR-structure. 相似文献