Searcharxiv⌕ Search

arXiv · math/0408316

Curvature homogeneous signature (2,2) manifolds

Abstract

We exhibit a family of generalized plane wave manifolds of signature (2,2). The geodesics in these manifolds extend for infinite time (i.e. they are complete), they are spacelike and timelike Jordan Osserman, and they are spacelike and timelike Jordan Ivanov-Petrova. Some are irreducible symmetric spaces. Some are homogeneous spaces but not symmetric. Some are 1-curvature homogeneous but not homogeneous. All are 0-modeled on the same irreducible symmetric space. We determine the Killing vector fields for these manifolds.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

C. Dunn, P. Gilkey, S. Nikcevic. 2004-08-23. Curvature homogeneous signature (2,2) manifolds. https://arxiv.org/abs/math/0408316

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Rotational symmetry of complete gradient Einstein-type manifolds with $α=0$ under vanishing conditions on several tensor fields

To provide a unified framework for various geometric solitons, Catino, Mastrolia, Monticelli, and Rigoli introduced gradient Einstein-type manifolds, which include gradient Yamabe solitons, gradient almost Yamabe solitons, gradient $k$-Yamabe solitons and conformal gradient solitons. In this paper, we show that any nontrivial complete four-dimensional gradient Einstein-type manifold with $α=0$, nonnegative scalar curvature, and vanishing Bach tensor is rotationally symmetric. The Bach-flat condition arises naturally in four-dimensional geometry and physics. We prove the main theorem by exploiting the conformal invariance of Bach-flatness and establishing a relation between two functionals. We also provide classification results under vanishing conditions on the Weyl tensor, the Cotton tensor, and the Cao-Chen-type tensor.

math.DG↗

The min-max width of spheres associated to the distance function

What one obtains when the min-max methods for the distance function are applied on the space of pairs of points of a Riemannian two-sphere? This question is studied in details in the present article. We show that the associated min-max width do not always coincide with half of the length of a simple closed geodesic which is the union of two minimizing geodesics with the same endpoints. Therefore, it is a new geometric invariant. We study the structure of the set of minimizing geodesics joining a pair of points realizing the width, and relationships between this invariant and the diameter. The extrinsic case of an embedded Riemannian sphere is also considered.

math.DG↗

On the $\mathcal{D}^+_J$ operator on higher-dimensional almost Kähler manifolds

In this paper, we introduce $\mathcal{D}^+_J$, a generalization of $\partial\bar{\partial}$ operator on higher dimensional almost Kähler manifolds. Using the $\mathcal{D}^+_J$ operator, we investigate the $\bar{\partial}$-problem in almost Kähler geometry and explore the generalized Monge-Ampère equation on almost Kähler manifolds. We establish uniqueness up to an additive constant. We also prove a local existence theorem for this equation on almost Kähler four-manifold. At last, we find an elliptical system for $\mathcal{D}^+_J$ operator. As an application, we reorganize the result of Tosatti-Weinkove-Yau in \cite{TWY}.

math.DG↗