13 papers
Einstein metrics, their moduli spaces and stability
Paul Schwahn, Uwe Semmelmann
This survey deals with two closely connected topics: first, the stability of Einstein metrics under the Einstein-Hilbert functional, and second, their deformation theory and the st…
The index of cubic focal manifolds
Niklas Rauchenberger, Uwe Semmelmann
We calculate the index and nullity of the three orientable focal manifolds of isoparametric hypersurfaces in spheres with three distinct principal curvatures. It turns out that the…
-structures with parallel skew-symmetric torsion
Andrei Moroianu, Uwe Semmelmann
We classify -dimensional Riemannian manifolds carrying a metric connection with parallel skew-symmetric torsion whose holonomy is contained in , up to naturally re…
Eigenvalue value estimates and stability of positive quaternion-Kähler manifolds
Yasushi Homma, Uwe Semmelmann
In this article we study the stability problem for positive quaternion-Kähler manifolds. We give a description of infinitesimal Einstein deformations and destabilising directions…
The Pestov identity on the frame bundle and associated homogeneous fibrations
Mihajlo CekiÄ, Thibault Lefeuvre, Andrei Moroianu +1
In this short note, we prove a global Pestov identity on the (orthonormal) frame bundle of a Riemannian manifold and deduce similar identities on associated homogeneous fibrations.…
Quaternionic-Kähler manifolds with nonnegative sectional curvature
S. Brendle, U. Semmelmann
We show that a compact quaternionic-Kähler manifold with positive scalar curvature and nonnegative sectional curvature is isometric to a symmetric space. This extends a classical…