Eigenvalues of a natural operator of centro-affine and graph hypersurfaces.
Ein Lemma über Polynome und seine Anwendungen
Eine Kennzeichnung der hyperbolischen Paraboloide bis auf Isometrien.
Epsilon Nielsen coincidence theory
We construct an epsilon coincidence theory which generalizes, in some aspect, the epsilon fixed point theory proposed by Robert Brown in 2006. Given two maps f, g: X → Y from a well-behaved topological space into a metric space, we define µ ∈(f, g) to be the minimum number of coincidence points of any maps f 1 and g 1 such that f 1 is ∈ 1-homotopic to f, g 1 is ∈ 2-homotopic to g and ∈ 1 + ∈ 2 < ∈. We prove that if Y is a closed Riemannian manifold, then it is possible to attain µ ∈(f, g) moving...
Essential parabolic structures and their infinitesimal automorphisms.
Examples of nonsemisymmetric Ricci-semisymmetric hypersurfaces
We construct a class of nonsemisymmetric Ricci-semisymmetric warped products. Some manifolds of this class can be locally realized as hypersurfaces of a semi-Euclidean space , n ≥ 5.
Existence of Metrics With Prescribed Ricci Curvature: Local Theory.
Extended Derdziński-Shen theorem for curvature tensors
We extend a remarkable theorem of Derdziński and Shen, on the restrictions imposed on the Riemann tensor by the existence of a nontrivial Codazzi tensor. We show that the Codazzi equation can be replaced by a more general algebraic condition. The resulting extension applies both to the Riemann tensor and to generalized curvature tensors.
Extremal domains for the first eigenvalue of the Laplace-Beltrami operator
We prove the existence of extremal domains with small prescribed volume for the first eigenvalue of Laplace-Beltrami operator in some Riemannian manifold. These domains are close to geodesic spheres of small radius centered at a nondegenerate critical point of the scalar curvature.