Scalar curvature of defineable CAT-spaces.
Several new characterizations of the sphere
Simplicial nonpositive curvature
We introduce a family of conditions on a simplicial complex that we call local k-largeness (k≥6 is an integer). They are simply stated, combinatorial and easily checkable. One of our themes is that local 6-largeness is a good analogue of the non-positive curvature: locally 6-large spaces have many properties similar to non-positively curved ones. However, local 6-largeness neither implies nor is implied by non-positive curvature of the standard metric. One can think of these results as a higher...
Sobre los cuerpos convexos de anchura constante en
Some Congruence Theorems for Closed Hypersurfaces in Riemann Spaces (Part III: Method baser on Voss' Proof)
Stability problems in a theorem of F. Schur.
Sur la rigidité de polyèdres hyperboliques en dimension : cas de volume fini, cas hyperidéal, cas fuchsien
Un polyèdre hyperbolique semi-idéal est un polyèdre dont les sommets sont dans l’espace hyperbolique ou à l’infini. Un polyèdre hyperbolique hyperidéal est, dans le modèle projectif, l’intersection de avec un polyèdre projectif dont les sommets sont tous en dehors de et dont toutes les arêtes rencontrent . Nous classifions les polyèdres semi-idéaux en fonction de leur métrique duale, d’après les résultats de Rivin dans [8] (écrit avec C.D.Hodgson) et [7]. Nous utilisons ce résultat pour retrouver...
Surfaces in and via spinors
We generalize the spinorial characterization of isometric immersions of surfaces in given by T. Friedrich to surfaces in and . The main argument is the interpretation of the energy-momentum tensor associated with a special spinor field as a second fundamental form. It turns out that such a characterization of isometric immersions in terms of a special section of the spinor bundle also holds in the case of hypersurfaces in the Euclidean -space.
Surfaces of Constant Mean Curvature Which Have a Simple Projection.
Symmetry of Hypersurfaces of Constant Mean Curvature with Symmetric Boundary.