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Let $(M,g_0)$ be a compact $n$-dimensional Riemannian manifold with a finite number of singular points, where the metric is asymptotic to a non-negatively curved cone over $(\mathbb{S}^{n-1},g)$. We show that there exists a smooth Ricci…

Differential Geometry · Mathematics 2018-12-19 Panagiotis Gianniotis , Felix Schulze

In this paper, first we consider the existence and non-existence of Einstein metrics on the topological 4-manifolds $3\mathbb{CP}^2 # k \bar{\mathbb{CP}}^2$ (for $k \in {11, 13, 14, 15, 16, 17, 18}$) by using the idea of R\u{a}sdeaconu and…

Differential Geometry · Mathematics 2012-08-27 Rafael Torres

Biconformal deformations take place in the presence of a conformal foliation, deforming by different factors tangent to and orthogonal to the foliation. Four-manifolds endowed with a conformal foliation by surfaces present a natural context…

Differential Geometry · Mathematics 2021-05-11 Paul Baird , Jade Ventura

This paper is devoted to the first systematic investigation of manifolds that are Einstein for a connection with skew symmetric torsion. We derive the Einstein equation from a variational principle and prove that, for parallel torsion, any…

Differential Geometry · Mathematics 2022-10-07 Ilka Agricola , Ana Cristina Ferreira

We establish codimension 4 regularity of noncollapsed sequences of metrics with bounds on natural generalizations of the Ricci tensor. We obtain a priori L2 curvature estimates on such spaces, with diffeomorphism finiteness results and…

Differential Geometry · Mathematics 2021-07-20 Xin Fu , Aaron Naber , Jeffrey Streets

Consider a Riemannian manifold with bounded Ricci curvature $|\Ric|\leq n-1$ and the noncollapsing lower volume bound $\Vol(B_1(p))>\rv>0$. The first main result of this paper is to prove that we have the $L^2$ curvature bound…

Differential Geometry · Mathematics 2020-10-29 Wenshuai Jiang , Aaron Naber

We set up an Einstein-Gauss-Bonnet theory in four dimensions, based on the recent formulation of pure gravity with extra dimensions of vanishing metrical length [1]. In absence of torsion, the effective field equations depend only on the…

General Relativity and Quantum Cosmology · Physics 2022-02-11 Sandipan Sengupta

We consider the Einstein constraints on asymptotically euclidean manifolds $M$ of dimension $n \geq 3$ with sources of both scaled and unscaled types. We extend to asymptotically euclidean manifolds the constructive method of proof of…

General Relativity and Quantum Cosmology · Physics 2012-08-27 Yvonne Choquet-Bruhat , James Isenberg , James W. York,

We prove that complete warped product Einstein metrics with isometric bases, simply connected space form fibers, and the same Ricci curvature and dimension are isometric. In the compact case we also prove that the warping functions must be…

Differential Geometry · Mathematics 2013-02-05 Chenxu He , Peter Petersen , William Wylie

Building on previous results, we complete the classification of compact oriented Einstein 4-manifolds with det (W^+) > 0. There are, up to diffeomorphism, exactly 15 manifolds that carry such metrics, and, on each of these manifolds, such…

Differential Geometry · Mathematics 2020-07-03 Claude LeBrun

Gompf's end-sum techniques are used to establish the existence of an infinity of non-diffeomorphic manifolds, all having the same trivial ${\bf R^4}$ topology, but for which the exotic differentiable structure is confined to a region which…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Carl H. Brans

We prove that there are infinitely many pairs of homeomorphic non-diffeomorphic smooth 4-manifolds, such that in each pair one manifold admits an Einstein metric and the other does not. We also show that there are closed 4-manifolds with…

Differential Geometry · Mathematics 2014-11-11 D. Kotschick

We give new examples of compact, negatively curved Einstein manifolds of dimension $4$. These are seemingly the first such examples which are not locally homogeneous. Our metrics are carried by a sequence of 4-manifolds $(X_k)$ previously…

Differential Geometry · Mathematics 2020-03-11 Joel Fine , Bruno Premoselli

In this paper, we derive the uniform L^{4}-bound of the transverse conic Ricci curvature along the conic Sasaki-Ricci flow on a compact transverse log Fano Sasakian manifold M of dimension five and the space of leaves of the characteristic…

Differential Geometry · Mathematics 2024-08-16 Shu-Cheng Chang , Fengjiang Li , Chien Lin , Chin-Tung Wu

In a recent article the first three authors proved that in dimension $4m+1$ all homotopy spheres that bound parallelizable manifolds admit Einstein metrics of positive scalar curvature which, in fact, are Sasakian-Einstein. They also…

Differential Geometry · Mathematics 2007-05-23 Charles P. Boyer , Krzysztof Galicki , János Kollár , Evan Thomas

In this paper, we obtain classification of four-dimensional Einstein manifolds with positive Ricci curvature and pinched sectional curvature. In particular, the first result concerns with an upper bound of sectional curvature, improving a…

Differential Geometry · Mathematics 2019-08-09 Xiaodong Cao , Hung Tran

We show that K\"ahler-Einstein metrics with cone singularities along simple normal crossing (SNC) divisors define RCD spaces, both in the compact setting and in certain non-compact cases, thereby producing many examples of Einstein RCD…

Differential Geometry · Mathematics 2026-01-27 Martin de Borbon , Cristiano Spotti

We prove the existence of Sasaki-Einstein metrics on certain simply connected 5-manifolds where until now existence was unknown. All of these manifolds have non-trivial torsion classes. On several of these we show that there are a countable…

Differential Geometry · Mathematics 2011-08-19 Charles P. Boyer , Michael Nakamaye

We prove that for a residual (and hence dense) subset $\mathcal{G}$ of Riemannian metrics on $S^{n+1}$ in the $C^{3}$ topology, no area-minimizing integral $n$-current that is a boundary admits a singular tangent cone which is linearly…

Differential Geometry · Mathematics 2026-04-17 Zehua Cheng

We study the structure of Gromov-Hausdorff limits of sequences of Riemannian manifolds $\{(M_\alpha^n,g_\alpha)\}_{\alpha \in A}$ whose Ricci curvature satisfies a uniform Kato bound. We first obtain Mosco convergence of the Dirichlet…

Differential Geometry · Mathematics 2024-10-30 Gilles Carron , Ilaria Mondello , David Tewodrose