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We establish a local equivalence between toric steady K\"ahler-Ricci solitons and $A$-type toric generalized K\"ahler-Ricci solitons (GKRS). Under natural global conditions we show this equivalence extends to complete GKRS, yielding a…

Differential Geometry · Mathematics 2025-09-04 Vestislav Apostolov , Giuseppe Barbaro , Jeffrey Streets , Yury Ustinovskiy

We develop a notion of Einstein manifolds with skew torsion on compact, orientable Riemannian manifolds of dimension four. We prove an analogue of the Hitchin-Thorpe inequality and study the case of equality. We use the link with…

Differential Geometry · Mathematics 2015-05-28 Ana Cristina Ferreira

We classify all scalar-flat toric K\"ahler 4-manifolds under either of two asymptotic conditions: that the action fields decay slowly (or at all), or that the curvature decay is quadratic; for example we fully classify instantons that have…

Differential Geometry · Mathematics 2021-04-05 Brian Weber

Motivated by understanding the limiting case of a certain systolic inequality we study compact Riemannian manifolds having all harmonic 1-forms of constant length. We give complete characterizations as far as K\"ahler and hyperbolic…

Differential Geometry · Mathematics 2008-10-10 Paul-Andi Nagy

We refine the regularity of noncollapsed limits of 5-dimensional manifolds with bounded Ricci curvature. In particular, for noncollapsed limits of Einstein 5-manifolds, we prove that (1) tangent cones are unique of the form…

Differential Geometry · Mathematics 2026-02-17 Yiqi Huang , Tristan Ozuch

The subject of this paper is the explicit momentum construction of complete Einstein metrics by ODE methods. Using the Calabi ansatz, further generalized by Hwang-Singer, we show that there are non-trivial complete conformally K\"ahler…

Differential Geometry · Mathematics 2021-11-02 Zhiming Feng

In the article we introduce new conformal and smooth invariants on compact, oriented four-manifolds with boundary. In the first part, we show that "positivity" conditions on these invariants will impose topological restrictions on…

Differential Geometry · Mathematics 2020-09-14 Siyi Zhang

For general compact K\"ahler manifolds it is shown that both Toeplitz quantization and geometric quantization lead to a well-defined (by operator norm estimates) classical limit. This generalizes earlier results of the authors and Klimek…

High Energy Physics - Theory · Physics 2009-10-22 Martin Bordemann , Eckhard Meinrenken , Martin Schlichenmaier

We analyze the horizon and geodesic structure of a class of 4D off--diagonal metrics with deformed spherical symmetries, which are exact solutions of the vacuum Einstein equations with anholonomic variables. The maximal analytic extension…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Sergiu Vacaru

The paper develops the fundamentals of quaternionic holomorphic curve theory. The holomorphic functions in this theory are conformal maps from a Riemann surface into the 4-sphere, i.e., the quaternionic projective line. Basic results such…

Differential Geometry · Mathematics 2009-10-31 D. Ferus , K. Leschke , F. Pedit , U. Pinkall

We analyze the classic problem of existence of Einstein metrics in a given conformal structure for the class of conformal structures inducedf Nurowski's construction by (oriented) (2,3,5) distributions. We characterize in two ways such…

Differential Geometry · Mathematics 2017-01-20 Katja Sagerschnig , Travis Willse

We present a uniform framework generalising and extending the classical theories of projective differential geometry, c-projective geometry, and almost quaternionic geometry. Such geometries, which we call \emph{projective parabolic…

Differential Geometry · Mathematics 2016-05-17 George E. Frost

This is a sequel to [Ca01]=math.AG/0110051. We define the bimeromorphic {\it category} of geometric orbifolds. These interpolate between (compact K\" ahler) manifolds and such manifolds with logarithmic structure. These geometric orbifolds…

Algebraic Geometry · Mathematics 2009-07-15 Frederic Campana

We define a new class of completions of locally symmetric varieties of type IV which interpolates between the Baily-Borel compactification and Mumford's toric compactifications. An arithmetic arrangement in a locally symmetric variety of…

Algebraic Geometry · Mathematics 2007-05-23 Eduard Looijenga

In this article we study the stability problem for the Einstein-Hilbert functional on compact symmetric spaces following and completing the seminal work of Koiso on the subject. We classify in detail the irreducible representations of…

Differential Geometry · Mathematics 2020-12-15 Uwe Semmelmann , Gregor Weingart

In this paper, we establish a compactness result for a class of conformally compact Einstein metrics defined on manifolds of dimension $d\ge 4$. As an application, we derive the global uniqueness of a class of conformally compact Einstein…

Differential Geometry · Mathematics 2026-01-29 Sun-Yung A. Chang , Yuxin Ge , Xiaoshang Jin , Jie Qing

Let $G$ be a simple compact connected Lie group. We study homogeneous Einstein metrics for a class of compact homogeneous spaces, namely generalized flag manifolds $G/H$ with second Betti number $b_{2}(G/H)=1$. There are 8 infinite families…

Differential Geometry · Mathematics 2019-11-25 Ioannis Chrysikos , Yusuke Sakane

Let $Y$ be a compact K\"ahler normal space and $\alpha \in H^{1,1}(Y,\mathbb{R})$ a K\"ahler class. We study metric properties of the space $\mathcal{H}_\alpha$ of K\"ahler metrics in $\alpha$ using Mabuchi geodesics. We extend several…

Differential Geometry · Mathematics 2019-02-20 Eleonora Di Nezza , Vincent Guedj

In this article we consider nonholonomic deformations of disk solutions in general relativity to generic off-diagonal metrics defining knew classes of exact solutions in 4D and 5D gravity. These solutions possess Lie algebroid symmetries…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Sergiu I. Vacaru

Peng Wu recently announced a beautiful characterization of conformally Kaehler, Einstein metrics of positive scalar curvature on compact oriented 4-manifolds via the condition det (W^+) > 0. In this note, we buttress his claim by providing…

Differential Geometry · Mathematics 2019-09-24 Claude LeBrun