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Let (M,g) a compact Riemannian n-dimensional manifold with umbilic boundary. It is well know that, under certain hypothesis, in the conformal class of g there are scalar-flat metrics that have the boundary of M as a constant mean curvature…

Analysis of PDEs · Mathematics 2019-03-27 Marco Ghimenti , Anna Maria Micheletti

We characterize manifolds which are locally conformally equivalent to either complex projective space or to its negative curvature dual in terms of their Weyl curvature tensor. As a byproduct of this investigation, we classify the…

Differential Geometry · Mathematics 2015-06-26 N. Blazic , P. Gilkey

In this paper, we classify $n$-dimensional ($n\geq 5$) quasi-Einstein manifolds with harmonic Weyl curvature, thus extending the work of Shin \cite{Shin} in dimension four for quasi-Einstein manifolds and refining the work of…

Differential Geometry · Mathematics 2025-12-01 Huai-Dong Cao , Fengjiang Li , James Siene

A famous theorem of Weyl states that if $M$ is a compact submanifold of euclidean space, then the volumes of small tubes about $M$ are given by a polynomial in the radius $r$, with coefficients that are expressible as integrals of certain…

Differential Geometry · Mathematics 2022-09-26 Joseph H. G. Fu , Thomas Wannerer

In the first part of this note we study compact Riemannian manifolds (M,g) whose Riemannian product with R is conformally Einstein. We then consider compact 6--dimensional almost Hermitian manifolds of type W_1+W_4 in the Gray--Hervella…

Differential Geometry · Mathematics 2019-01-08 Andrei Moroianu , Liviu Ornea

Following the approach to pseudo-Riemannian symmetric spaces developed in math.DG/0408249 we exhibit examples of indefinite hyper-Kaehler symmetric spaces with non-abelian holonomy. Moreover, we classify indecomposable hyper-Kaehler…

Differential Geometry · Mathematics 2007-05-23 Ines Kath , Martin Olbrich

The Weyl principle is extended from the Riemannian to the pseudo-Riemannian setting, and subsequently to manifolds equipped with generic symmetric $(0,2)$-tensors. More precisely, we construct a family of generalized curvature measures…

Differential Geometry · Mathematics 2022-09-14 Andreas Bernig , Dmitry Faifman , Gil Solanes

The difference tensor R.C-C.R of a semi-Riemannian manifold (M,g), dim M > 3, formed by its Riemannian-Christoffel curvature tensor R and the Weyl conformal curvature tensor C, under some assumptions, can be expressed as a linear…

In this paper a thorough study of the normal form and the first integrability conditions arising from {\em bi-conformal vector fields} is presented. These new symmetry transformations were introduced in {\em Class. Quantum…

Mathematical Physics · Physics 2016-08-16 Alfonso García-Parrado Gómez-Lobo

We descrive examples of metrics in the conformal class $[g]$ on complete conformally flat Riemannian manifolds $(M,g].$ These metrics have a constant scalar curvature and an harmonic curvature with non parallel Ricci tensor.

Differential Geometry · Mathematics 2007-05-23 A. Raouf Chouikha

The existence of a recurrent spinor field on a pseudo-Riemannian spin manifold $(M,g)$ is closely related to the existence of a parallel 1-dimensional complex subbundle of the spinor bundle of $(M,g)$. We characterize the following simply…

Differential Geometry · Mathematics 2018-08-21 Anton S. Galaev

In this paper we provide a new method for establishing the rotational symmetry of the solutions to a couple of very classical overdetermined problems arising in potential theory, in both the exterior and the interior punctured domain.…

Analysis of PDEs · Mathematics 2015-02-19 Virginia Agostiniani , Lorenzo Mazzieri

We analyze the structure of the set of limiting Carleman weights in all conformally flat manifolds, 3-manifolds, and 4-manifolds. In particular we give a new proof of the classification of Euclidean limiting Carleman weights, and show that…

Analysis of PDEs · Mathematics 2018-11-07 Pablo Angulo-Ardoy , Daniel Faraco , Luis Guijarro , Mikko Salo

In this article, we study quasi-Einstein manifolds with constant scalar curvature. We provide a classification of compact and noncompact (possibly with boundary) $T$-flat quasi-Einstein manifolds with constant scalar curvature, where the…

Differential Geometry · Mathematics 2025-05-27 Johnatan Costa , Ernani Ribeiro , Márcio Santos

A metric projective structure is a manifold equipped with the unparametrised geodesics of some pseudo-Riemannian metric. We make acomprehensive treatment of such structures in the case that there is a projective Weyl curvature nullity…

Differential Geometry · Mathematics 2017-11-28 A. Rod Gover , Vladimir S. Matveev

Let (M,g) be a 2-quasi-Einstein non-conformally flat semi-Riemannian manifold of dimension > 3. We prove that if its Riemann-Christoffel curvature tensor R is a linear combination of some Kulkarni-Nomizu tensors formed by the metric tensor…

We give a new proof of the existence of nontrivial quasimeromorphic mappings on a smooth Riemannian manifold, using solely the intrinsic geometry of the manifold.

Complex Variables · Mathematics 2010-05-12 Emil Saucan

We introduce the new algebraic property of Weyl compatibility for symmetric tensors and vectors. It is strictly related to Riemann compatibility, which generalizes the Codazzi condition while preserving much of its geometric implications.…

Mathematical Physics · Physics 2016-03-10 Carlo A. Mantica , Luca G. Molinari

We give a classification of many closed Riemannian manifolds M whose universal cover possesses a nontrivial amount of symmetry. More precisely, we consider closed Riemannian manifolds $M$ such that Isom$(\widetilde{M})$ has noncompact…

Differential Geometry · Mathematics 2014-05-12 Wouter van Limbeek

We classify flat strict nearly K\"ahler manifolds with (necessarily) indefinite metric. Any such manifold is locally the product of a flat pseudo-K\"ahler factor of maximal dimension and a strict flat nearly K\"ahler manifold of split…

Differential Geometry · Mathematics 2007-05-23 Vicente Cortés , Lars Schäfer