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We consider the significant class of holomorphically nondegenerate CR manifolds of finite type that are represented by some weighted homogeneous polynomials and we derive some useful features which enable us to set up a fast effective…

Differential Geometry · Mathematics 2014-01-21 Masoud Sabzevari , Amir Hashemi , Benyamin M. -Alizadeh , Joel Merker

We show the existence of a compact K\"ahler manifold which does not fit in a proper flat family over an irreducible base with one projective (possibly singular) fiber. We also give a topological version of this statement. This strengthens…

Algebraic Geometry · Mathematics 2022-08-23 Claire Voisin

We reduce CR-structures on smooth elliptic and hyperbolic manifolds of CR-codimension 2 to parallelisms thus solving the problem of global equivalence for such manifolds. The parallelism that we construct is defined on a sequence of two…

Complex Variables · Mathematics 2007-05-23 V. V. Ezhov , A. V. Isaev , G. Schmalz

We study the minimality of an isometric immersion of a Riemannian manifold into a strictly pseudoconvex CR manifold endowed with the Webster metric hence formulate a version of the CR Yamabe problem for CR manifolds-with-boundary. This is…

Differential Geometry · Mathematics 2007-05-23 Sorin Dragomir

We show that the vanishing of the higher dimensional homology groups of a manifold ensures that every almost CR structure of codimension $k$ may be homotoped to a CR structure. This result is proved by adapting a method due to Haefliger…

Complex Variables · Mathematics 2014-05-09 Howard Jacobowitz , Peter Landweber

We determine a 2-codimensional CR-structure on the slit tangent bundle $T_0M$ of a Finsler manifold $(M, F)$ by imposing a condition regarding the almost complex structure $\Psi$ associated to $F$ when restricted to the structural…

Differential Geometry · Mathematics 2016-08-11 Mircea Crasmareanu , Laurian-Ioan Pişcoran

We prove two rigidity results on holomorphic isometries into homogeneous K\"{a}hler manifolds. The first shows that a K\"{a}hler-Ricci soliton induced by the homogeneous metric of the K\"{a}hler product of a special flag manifold (i.e. a…

Differential Geometry · Mathematics 2024-06-11 A. Loi , R. Mossa

We show that non-degenerate hyperquadrics in R^{n+2} admit no skew branes. Stated more traditionally, a compact codimension-one immersed submanifold of a non-degenerate hyperquadric of euclidean space must have parallel tangent spaces at…

Differential Geometry · Mathematics 2007-05-23 Ji-Ping Sha , Bruce Solomon

In the first part, Hyperkaehler Embeddings and Holomorphic symplectic Geometry I, we prove the following. Let $N$ be a closed analytic subvariety of a generic deformation of a holomorphically symplectic compact manifold $M$. Then the…

alg-geom · Mathematics 2008-02-03 Misha Verbitsky

Let $M=X\times Y$ be the product of two complex manifolds of positive dimensions. In this paper, we prove that there is no complete K\"ahler metric $g$ on $M$ such that: either (i) the holomorphic bisectional curvature of $g$ is bounded by…

Differential Geometry · Mathematics 2009-09-30 Luen-Fai Tam , Chengjie Yu

In a recent paper, the author and I. Zelenko introduce the concept of modified CR symbols for organizing local invariants of $2$-nondegenerate CR structures. In this paper, we consider homogeneous hypersurfaces in $\mathbb{C}^4$, a natural…

Differential Geometry · Mathematics 2023-06-09 David Sykes

We give an invariant nondegeneracy condition for CR--maps between generic submanifolds in different dimensions and use it to prove a reflection principle for these maps.

Complex Variables · Mathematics 2007-05-23 Bernhard Lamel

Gravity duals for a class of UV complete minimally supersymmetric non-conformal gauge theories require deformed conifolds with fluxes. However these manifolds do not allow for the standard Kahler or conformally Kahler metrics on them,…

High Energy Physics - Theory · Physics 2018-06-07 Keshav Dasgupta , Jake Elituv , Maxim Emelin , Anh-Khoi Trinh

We study biwarped product submanifolds which are special cases of multiply warped product submanifolds in K\"{a}hler manifolds. We observe the non-existence of such submanifolds under some circumstances. We show that there exists a…

Differential Geometry · Mathematics 2017-01-11 Hakan Mete Taştan

This paper is a sequel to arXiv:1012.2940. We further investigate the Gromov-Hausdorff convergence of Ricci-flat K\"{a}hler metrics under degenerations of Calabi-Yau manifolds. We extend Theorem 1.1 in arXiv:1012.2940 by removing the…

Differential Geometry · Mathematics 2014-01-30 Xiaochun Rong , Yuguang Zhang

The CR $\delta$-invariant for CR-submanifolds was introduced in a recent article [B. Y. Chen, An optimal inequality for CR-warped products in complex space forms involving CR $\delta$-invariant, Internat. J. Math. 23} (2012), no. 3, 1250045…

Differential Geometry · Mathematics 2013-07-10 Falleh R. Al-Solamy , Bang-Yen Chen , Sharief Deshmukh

We construct a compact K\"ahler manifold of nonnegative quadratic bisectional curvature, which does not admit any K\"ahler metric of nonnegative orthogonal bisectional curvature. The manifold is a 7-dimensional K\"ahler C-space with second…

Differential Geometry · Mathematics 2011-10-11 Qun Li , Damin Wu , Fangyang Zheng

We propose two constructions extending the Chern-Moser normal form to non-integrable Levi-nondegenerate (hypersurface type) almost CR structures. One of them translates the Chern-Moser normalization into pure intrinsic setting, whereas the…

Complex Variables · Mathematics 2017-10-16 Dmitri Zaitsev

We study, from the point of view of CR geometry, the orbits M of a real form G of a complex semisimple Lie group G in a complex flag manifold G/Q. In particular we characterize those that are of finite type and satisfy some Levi…

Complex Variables · Mathematics 2007-05-23 Andrea Altomani , Costantino Medori , Mauro Nacinovich

We prove that under certain conditions on the mean curvature and on the Kaehler angles, a compact submanifold M of real dimension 2n, immersed into a Kaehler-Einstein manifold N of complex dimension 2n, must be either a complex or a…

Differential Geometry · Mathematics 2007-05-23 Isabel M. C. Salavessa