Compact Einstein warped product spaces with nonpositive scalar curvature

Warped product and quasi-Einstein metrics

Warped products provide a rich class of physically significant geometric objects. Warped product construction is an important method to produce a new metric with a base manifold and a fibre. We construct compact base manifolds with a positive scalar curvature which do not admit any non-trivial quasi-Einstein warped product, and non compact complete base manifolds which do not admit any non-triv...

Compact Kähler Manifolds with Nonpositive Bisectional Curvature

Let (Mn, g) be a compact Kähler manifold with nonpositive bisectional curvature. We show that a finite cover is biholomorphic and isometric to a flat torus bundle over a compact Kähler manifold Nk with c1 < 0. This confirms a conjecture of Yau. As a corollary, for any compact Kähler manifold with nonpositive bisectional curvature, the Kodaira dimension is equal to the maximal rank of the Ricci ...

Schauder Fixed Point Theorem in Spaces with Global Nonpositive Curvature

On the Scalar Curvature of Einstein Manifolds

We show that there are high-dimensional smooth compact manifolds which admit pairs of Einstein metrics for which the scalar curvatures have opposite signs. These are counter-examples to a conjecture considered by Besse [6, p. 19]. The proof hinges on showing that the Barlow surface has small deformations with ample canonical line bundle.

Compact Space-like Hypersurfaces with Constant Scalar Curvature in Locally Symmetric Lorentz Spaces

Let Nn+p p be an (n + p)-dimensional connected semi-Riemannian manifold of index p. It is called a semi-definite space of index p. When we refer to index p, we mean that there are only p negative eigenvalues of semi-Riemannian metric of Nn+p p and the other eigenvalues are positive. In particular, Nn+1 1 is called a Lorentz space when p = 1. When the Lorentz space Nn+1 1 is of constant curvatur...