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Related papers: K-Semistability for irregular Sasakian manifolds

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Given an SO(3)-bundle with connection, the associated two-sphere bundle carries a natural closed 2-form. Asking that this be symplectic gives a curvature inequality first considered by Reznikov. We study this inequality in the case when the…

Symplectic Geometry · Mathematics 2017-03-24 Joel Fine , Dmitri Panov

We consider the problem of existence of constant scalar curvature Kaehler metrics on complete intersections of sections of vector bundles. In particular we give general formulas relating the Futaki invariant of such a manifold to the weight…

Algebraic Geometry · Mathematics 2019-09-12 Claudio Arezzo , Alberto Della Vedova

A Calabi-Yau threefold is called of type K if it admits an \'etale Galois covering by the product of a K3 surface and an elliptic curve. In our previous paper, based on Oguiso-Sakurai's fundamental work, we provide the full classification…

Algebraic Geometry · Mathematics 2016-06-22 Kenji Hashimoto , Atsushi Kanazawa

In this thesis we study the relationship between the existence of canonical metrics on a complex manifold and stability in the sense of geometric invariant theory. We introduce a modification of K-stability of a polarised variety which we…

Differential Geometry · Mathematics 2007-05-23 Gábor Székelyhidi

The orthogonal decomposition of the Webster curvature provides us a way to characterize some canonical metrics on a pseudo-Hermitian manifold. We derive some subelliptic differential inequalities from the Weitzenb\"ock formulas for the…

Differential Geometry · Mathematics 2014-02-28 Yuxin Dong , Hezi Lin , Yibin Ren

In this paper, we shall show that a polarized algebraic manifold is K-stable if the polarization class admits a Kaehler metric of constant scalar curvature. This generalizes the results of Chen-Tian, Donaldson and Stoppa. (Parts of the…

Differential Geometry · Mathematics 2008-12-30 Toshiki Mabuchi

We find some curvature properties of 3-quasi-Sasakian manifolds which are similar to some well-known identities holding in the Sasakian case. As an application, we prove that any 3-quasi-Sasakian manifold of constant horizontal sectional…

Differential Geometry · Mathematics 2013-08-13 Beniamino Cappelletti Montano , Antonio De Nicola , Ivan Yudin

We use the correspondence between extremal Sasaki structures and weighted extremal Kahler metrics defined on a regular quotient of a Sasaki manifold, established by the first two authors, and Lahdili's theory of weighted K-stability in…

Differential Geometry · Mathematics 2020-12-17 Vestislav Apostolov , David M. J. Calderbank , Eveline Legendre

K-polystability of a polarised variety is an algebro-geometric notion conjecturally equivalent to the existence of a constant scalar curvature K\"ahler metric. When a variety is K-unstable, it is expected to admit a "most destabilising"…

Algebraic Geometry · Mathematics 2020-04-01 Ruadhaí Dervan

We investigate L-sectional curvature of S-manifolds with respect to the Rieman- nian connection and to certain semi-symmetric metric and non-metric connections naturally related with the structure, obtaining conditions for them to be…

Differential Geometry · Mathematics 2013-04-23 Mehmet Akif Akyol , Luis M. FernÁndez , Alicia Prieto-MartÍn

We consider deformations of the scalar curvature of a partially integrable pseudohermitian manifold, in analogy with the work of Fischer and Marsden on Riemannian manifolds. In particular, we introduce and discuss $R$-singular spaces, give…

Differential Geometry · Mathematics 2024-04-11 Jeffrey S. Case , Pak Tung Ho

Extending a result of He to the non-integrable case of K-contact manifolds, it is shown that transverse Hermitian scalar curvature may be interpreted as a moment map for the strict contactomorphism group. As a consequence, we may generalize…

Differential Geometry · Mathematics 2014-10-07 Mehdi Lejmi , Markus Upmeier

In this paper, we concern with the Sasaki analogue of Yau uniformization conjecture in a complete noncompact Sasakian manifold with nonnegative transverse bisectional curvature. As a consequence, we confirm that any $5$-dimensional complete…

Differential Geometry · Mathematics 2026-01-16 Shu-Cheng Chang , Yingbo Han , Chien Lin , Chin-Tung Wu

We study the problem of estimating a manifold from random samples. In particular, we consider piecewise constant and piecewise linear estimators induced by k-means and k-flats, and analyze their performance. We extend previous results for…

Machine Learning · Computer Science 2015-03-20 Guillermo D. Canas , Tomaso Poggio , Lorenzo Rosasco

We discuss Sasakian-Einstein geometry under a quasi-regularity assumption. It is shown that the space of all quasi-regular Sasakian-Einstein orbifolds has a natural multiplication on it. Furthermore, necessary and sufficient conditions are…

Differential Geometry · Mathematics 2007-05-23 Charles P. Boyer , Krzysztof Galicki

We introduce a parametrized version of scissors congruence $K$-theory of manifolds with tangential structure, which includes a topologized version of the scissors congruence $K$-theory of oriented manifolds as a special case. We examine the…

Algebraic Topology · Mathematics 2026-04-03 Mona Merling , George Raptis , Julia Semikina

We present reformulation of Mathieu's result on representing cohomology classes of symplectic manifold with symplectically harmonic forms. We apply it to the case of foliated manifolds with transversally symplectic structure and to…

Differential Geometry · Mathematics 2010-01-15 Lukasz Bak , Andrzej Czarnecki

We express notions of K-stability of polarized spherical varieties in terms of combinatorial data, vastly generalizing the case of toric varieties. We then provide a combinatorial sufficient condition of G-uniform K-stability by studying…

Algebraic Geometry · Mathematics 2026-03-25 Thibaut Delcroix

We present some examples of curvature homogeneous pseudo-Riemannian manifolds which are k-spacelike Jordan Stanilov; their higher order curvature operator has constant Jordan normal form on the Grassmannian of unoriented k-dimensional…

Differential Geometry · Mathematics 2007-05-23 P. Gilkey , S. Nikcevic , V. Videv

This paper mainly focuses on the CR analogue of the three-circle theorem in a complete noncompact pseudohermitian manifold of vanishing torsion being odd dimensional counterpart of K\"ahler geometry. In this paper, we show that the CR…

Differential Geometry · Mathematics 2018-01-31 Shu-Cheng Chang , Yingbo Han , Chien Lin