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We compute Hoelder Complexes,i.e. the complete bi-Lipschitz invariants, for germs of real weighed homogeneous algebraic or semialgebraic surfaces.

Algebraic Geometry · Mathematics 2007-12-18 Lev Birbrair , Alexandre Fernandes

By using analytic method, we prove that there exist rational curves on compact Hermitian manifolds with positive holomorphic bisectional curvature. It confirms a question of S.-T. Yau. It is well-known that Mori proved in \cite{Mori79} that…

Differential Geometry · Mathematics 2014-10-07 Huitao Feng , Kefeng Liu , Xueyuan Wan , Xiaokui Yang

A new construction is presented of scalar-flat Kaehler metrics on non-minimal ruled surfaces. The method is based on the resolution of singularities of orbifold ruled surfaces which are closely related to rank-2 parabolically stable…

Differential Geometry · Mathematics 2007-05-23 Yann Rollin , Michael A. Singer

For singular metrics, there is no Quillen metric formalism on cohomology determinant. In this paper, we develop an admissible theory, with which the arithmetic Deligne-Riemann-Roch isometry can be established for singular metrics. As an…

Algebraic Geometry · Mathematics 2007-05-23 Lin Weng

We study the compact Hermitian spin surfaces with positive conformal scalar curvature on which the first eigenvalue of the Dolbeault operator of the spin structure is the smallest possible. We prove that such a surface is either a ruled…

Differential Geometry · Mathematics 2007-05-23 Bogdan Alexandrov

We study the existence of three classes of Hermitian metrics on certain types of compact complex manifolds. More precisely, we consider balanced, SKT and astheno-K\"ahler metrics. We prove that the twistor spaces of compact hyperk\"ahler…

Differential Geometry · Mathematics 2018-02-08 Anna Fino , Gueo Grantcharov , Luigi Vezzoni

We prove several K\"ahlerness criteria for compact Hermitian surfaces under semi-definiteness assumptions on natural Ricci curvatures of the Strominger-Bismut connection. The key tools for proving these results are explicit identities…

Differential Geometry · Mathematics 2026-05-27 Liangdi Zhang

We study Hermitian metrics with constant second scalar curvature on compact manifolds. We first consider a Yamabe-type problem for the second Bismut scalar curvature under a natural topological condition, and then analyze elliptic equations…

Differential Geometry · Mathematics 2026-01-29 Liangdi Zhang

We prove the formality and the evenness of odd-degree Betti numbers for compact K\"ahler orbifolds, by adapting the classical proofs for K\"ahler manifolds. As a consequence, we obtain examples of symplectic orbifolds not admitting any…

Differential Geometry · Mathematics 2016-12-30 Giovanni Bazzoni , Indranil Biswas , Marisa Fernández , Vicente Muñoz , Aleksy Tralle

We show that, on an oriented compact surface, two sufficiently $C^2$-close Riemannian metrics with strictly convex boundary, no conjugate points, hyperbolic trapped set for their geodesic flows, and same marked boundary distance, are…

Differential Geometry · Mathematics 2018-05-08 Colin Guillarmou , Marco Mazzucchelli

In this paper, we prove that, a compact complex manifold $X$ admits a smooth Hermitian metric with positive (resp. negative) scalar curvature if and only if $K_X$ (resp. $K_X^{-1}$) is not pseudo-effective. On the contrary, we also show…

Differential Geometry · Mathematics 2017-10-12 Xiaokui Yang

Exceptional points at which eigenvalues and eigenvectors of non-Hermitian matrices coalesce are ubiquitous in the description of a wide range of platforms from photonic or mechanical metamaterials to open quantum systems. Here, we introduce…

Mesoscale and Nanoscale Physics · Physics 2026-01-08 Tsuneya Yoshida , Emil J. Bergholtz , Tomáš Bzdušek

We define a partition of the space of projectively flat metrics in three classes according to the sign of the Chern scalar curvature; we prove that the class of negative projectively flat metrics is empty, and that the class of positive…

Differential Geometry · Mathematics 2021-03-25 Simone Calamai

Motivated by considerations of euclidean quantum gravity, we investigate a central question of spectral geometry, namely the question of reconstructability of compact Riemannian manifolds from the spectra of their Laplace operators. To this…

Differential Geometry · Mathematics 2017-12-01 Mikhail Panine , Achim Kempf

We wish to attack the problems that H.~Anciaux and K.~Panagiotidou posed in [1], for non-degenerate real hypersurfaces in indefinite complex projective space. We will slightly change these authors' point of view, obtaining cleaner equations…

Differential Geometry · Mathematics 2019-02-18 Makoto Kimura , Miguel Ortega

We consider the results of combining two approaches developed for the design of Riemannian metrics on curves and surfaces, namely parametrization-invariant metrics of the Sobolev type on spaces of immersions, and metrics derived through…

Differential Geometry · Mathematics 2018-04-24 Laurent Younes

Let (M,I) be a compact Kaehler manifold admitting a hypercomplex structure. We show that (M, I) admits a natural HKT-metric. This is used to construct a holomorphic symplectic form on (M,I).

Algebraic Geometry · Mathematics 2007-05-23 Misha Verbitsky

We obtain a local classification of complex homothetic foliations on Kaehler manifolds by complex curves. This is used to construct almost Kaehler, Ricci-flat metrics subject to additional curvature properties.

Differential Geometry · Mathematics 2012-06-18 Simon G. Chiossi , Paul-Andi Nagy

We prove that a complete noncompact K\"ahler surface with positive and bounded sectional curvature is biholomorphic to $\mathbb{C}^2$. This result confirms a special case of Yau's conjecture that a complete noncompact K\"ahler $n$-manifold…

Differential Geometry · Mathematics 2025-11-11 Ved Datar , Vamsi Pritham Pingali , Harish Seshadri

We establish a uniformization result for metric surfaces - metric spaces that are topological surfaces with locally finite Hausdorff 2-measure. Using the geometric definition of quasiconformality, we show that a metric surface that can be…

Complex Variables · Mathematics 2019-09-20 Toni Ikonen