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We show that any Riemannian metric conformal to the round metric on $S^n$, for $n\geq 4$, arises as a limit of a sequence of Riemannian metrics of positive scalar curvature on $S^n$ in the sense of uniform convergence of Riemannian…

Differential Geometry · Mathematics 2024-11-19 Man-Chun Lee , Peter M. Topping

We classify $n$-dimensional geometric graph manifolds with nonnegative scalar curvature, and first show that if $n>3$, the universal cover splits off a codimension 3 Euclidean factor. We then proceed with the classification of the…

Differential Geometry · Mathematics 2021-09-17 Luis Florit , Wolfgang Ziller

We initiate the study of an analogue of the Yamabe problem for complex manifolds. More precisely, fixed a conformal Hermitian structure on a compact complex manifold, we are concerned in the existence of metrics with constant Chern scalar…

Differential Geometry · Mathematics 2017-09-05 Daniele Angella , Simone Calamai , Cristiano Spotti

In this note, we investigate conformally flat submanifolds of Euclidean space with positive index of relative nullity. Let $M^n$ be a complete conformally flat manifold and let $f\colon M^n\to \R^m$ be an isometric immersion. We prove the…

Differential Geometry · Mathematics 2019-05-23 Christos-Raent Onti

We generalise the classical Chern-Gauss-Bonnet formula to a class of 4-dimensional manifolds with finitely many conformally flat ends and singular points. This extends results of Chang-Qing-Yang in the smooth case. Under the assumptions of…

Differential Geometry · Mathematics 2021-10-14 Reto Buzano , Huy The Nguyen

We study the problem of deforming a Riemannian metric to a conformal one with nonzero constant scalar curvature and nonzero constant boundary mean curvature on a compact manifold of dimension $n\geq 3$. We prove the existence of such…

Differential Geometry · Mathematics 2018-04-20 Xuezhang Chen , Liming Sun

It is shown that if a compact four-dimensional manifold with metric of neutral signature is Jordan-Osserman, then it is either of constant sectional curvature or Ricci flat.

Differential Geometry · Mathematics 2010-04-08 M. Brozos-Vazquez , E. Garcia-Rio , P. Gilkey , R. Vazquez-Lorenzo

We consider balanced metrics on complex manifolds with holomorphically trivial canonical bundle, most commonly known as balanced $\rm{SU}(n)$-structures. Such structures are of interest for both Hermitian geometry and string theory, since…

Differential Geometry · Mathematics 2025-02-28 Izar Alonso , Francesca Salvatore

A hypercomplex structure on a differentiable manifold consists of three integrable almost complex structures that satisfy quaternionic relations. If, in addition, there exists a metric on the manifold which is Hermitian with respect to the…

Differential Geometry · Mathematics 2019-08-13 Artour Tomberg

We obtain topological obstructions to the existence of a complete Riemannian metric with uniformly positive scalar curvature on certain (non-compact) $4$-manifolds. In particular, such a metric on the interior of a compact contractible…

Differential Geometry · Mathematics 2024-07-09 Otis Chodosh , Davi Maximo , Anubhav Mukherjee

In this paper, we classify compact simply connected cohomogeneity one manifolds up to equivariant diffeomorphism whose isotropy representation by the connected component of the principal isotropy subgroup has three or less irreducible…

Differential Geometry · Mathematics 2010-06-03 Chenxu He

Using the Chern-Gauss-Bonnet theorem, we establish a sharp inequality for the total Gauss-Kronecker curvature of convex hypersurfaces in Cartan-Hadamard manifolds $M^n$ with nullity index at least $n-3$. Consequently, the Euclidean…

Differential Geometry · Mathematics 2026-05-26 Mohammad Ghomi

We study the spectrum of complete noncompact manifolds with bounded curvature and positive injectivity radius. We give general conditions which imply that their essential spectrum has an arbitrarily large finite number of gaps. In…

Spectral Theory · Mathematics 2017-11-15 Richard Schoen , Hung Tran

In this short note, we will prove a volume stability theorem which says that if an n-dimensional toric manifold $M$ admits a $\mathbb{T}^n$ invariant K\"ahler metric $\omega$ with Ricci curvature no less than 1 and its volume is close to…

Differential Geometry · Mathematics 2012-10-23 Wang Feng

Motivated by the work of Li and Mantoulidis, we study singular metrics which are uniformly Euclidean $(L^\infty)$ on a compact manifold $M^n$ ($n\ge 3$) with negative Yamabe invariant $\sigma(M)$. It is well-known that if $g$ is a smooth…

Differential Geometry · Mathematics 2021-07-20 Man-Chuen Cheng , Man-Chun Lee , Luen-Fai Tam

We prove index estimates for closed and free boundary CMC surfaces in certain $3$-dimensional submanifolds of some Euclidean space. When the mean curvature is large enough we are able to prove that the index of a CMC surface in an arbitrary…

Differential Geometry · Mathematics 2019-01-30 Nicolau S. Aiex , Han Hong

We prove that for any complete n-dimensional Riemannian manifold with nonnegative Ricci curvature, if the Nash inequality is satisfied, then it is diffeomorphic to $R^{n}$l.

Differential Geometry · Mathematics 2007-05-23 Qihua Ruan , Zhihua Chen

We will give a simple proof that the metric of any compact Yamabe gradient soliton (M,g) is a metric of constant scalar curvature when the dimension of the manifold n>2.

Differential Geometry · Mathematics 2011-07-20 Shu-Yu Hsu

A Kaehler metric $g$ with integral Kaehler form is said to be partially regular if the partial Bergman kernel associated to mg is a positive constant for all integer m sufficiently large. The aim of this paper is to prove that for all n\geq…

Differential Geometry · Mathematics 2020-06-23 Andrea Loi , Fabio Zudda

Evolving smooth, compact hypersurfaces in R^{n+1} with normal speed equal to a positive power k of the mean curvature improves a certain 'isoperimetric difference' for k >= n-1. As singularities may develop before the volume goes to zero,…

Differential Geometry · Mathematics 2007-05-23 Felix Schulze