Displaying 161 – 180 of 283

Showing per page

Holonomy groups of complete flat manifolds

Michał Sadowski (2007)

Banach Center Publications

We present short direct proofs of two known properties of complete flat manifolds. They say that the diffeomorphism classes of m-dimensional complete flat manifolds form a finite set S C F ( m ) and that each element of S C F ( m ) is represented by a manifold with finite holonomy group.

Holonomy, twisting cochains and characteristic classes

G. Sharygin (2011)

Annales de la faculté des sciences de Toulouse Mathématiques

This paper contains a description of various geometric constructions associated with fibre bundles, given in terms of important algebraic object, the “twisting cochain". Our examples include the Chern-Weil classes, the holonomy representation and the so-called cyclic Chern character of Bismut and others (see [2, 11, 27]), also called the Bismut’s class. The later example is the principal one for us, since we are motivated by the attempt to find an algebraic approach to the Witten’s index formula....

Homogénéité locale pour les métriques riemanniennes holomorphes en dimension 3

Sorin Dumitrescu (2007)

Annales de l’institut Fourier

Une métrique riemannienne holomorphe sur une variété complexe M est une section holomorphe q du fibré S 2 ( T * M ) des formes quadratiques complexes sur l’espace tangent holomorphe à M telle que, en tout point m de M , la forme quadratique complexe q ( m ) est non dégénérée (de rang maximal, égal à la dimension complexe de M ). Il s’agit de l’analogue, dans le contexte holomorphe, d’une métrique riemannienne (réelle). Contrairement au cas réel, l’existence d’une telle métrique sur une variété complexe compacte n’est...

Homogeneous bundles and the first eigenvalue of symmetric spaces

Leonardo Biliotti, Alessandro Ghigi (2008)

Annales de l’institut Fourier

In this note we prove the stability of the Gieseker point of an irreducible homogeneous bundle over a rational homogeneous space. As an application we get a sharp upper estimate for the first eigenvalue of the Laplacian of an arbitrary Kähler metric on a compact Hermitian symmetric spaces of ABCD–type.

Homogeneous Cartan geometries

Matthias Hammerl (2007)

Archivum Mathematicum

We describe invariant principal and Cartan connections on homogeneous principal bundles and show how to calculate the curvature and the holonomy; in the case of an invariant Cartan connection we give a formula for the infinitesimal automorphisms. The main result of this paper is that the above calculations are purely algorithmic. As an example of an homogeneous parabolic geometry we treat a conformal structure on the product of two spheres.

Homogeneous Einstein manifolds based on symplectic triple systems

Cristina Draper Fontanals (2020)

Communications in Mathematics

For each simple symplectic triple system over the real numbers, the standard enveloping Lie algebra and the algebra of inner derivations of the triple provide a reductive pair related to a semi-Riemannian homogeneous manifold. It is proved that this is an Einstein manifold.

Currently displaying 161 – 180 of 283