Let be an affine conical factorial variety over an algebraically closed field of characteristic zero. We consider equidimensional and stable algebraic actions of an algebraic torus on compatible with the conical structure. We show that such actions are cofree and the nullcones of associated with them are complete intersections.
We consider locally standard 2-torus manifolds, which are a generalization of small covers of Davis and Januszkiewicz and study their equivariant classification. We formulate a necessary and sufficient condition for two locally standard 2-torus manifolds over the same orbit space to be equivariantly homeomorphic. This leads us to count the equivariant homeomorphism classes of locally standard 2-torus manifolds with the same orbit space.
V. Alexeev and M. Brion introduced, for a given a complex reductive group, a moduli scheme of affine spherical varieties with prescribed weight monoid. We provide new examples of this moduli scheme by proving that it is an affine space when the given group is of type and the prescribed weight monoid is that of a spherical module.
We obtain several several results on the multiplicative structure constants of the T-equivariant Grothendieck ring of the flag variety G/B. We do this by lifting the classes of the structure sheaves of Schubert varieties in to R(T) ⊗ R(T), where R(T) denotes the representation ring of the torus T. We further apply our results to describe the multiplicative structure constants of where X denotes the wonderful compactification of the adjoint group of G, in terms of the structure constants of...
Given a complex manifold M equipped with an action of a group G, and a holomorphic principal H–bundle EH on M, we introduce the notion of a connection on EH along the action of G, which is called a G–connection. We show some relationship between the condition that EH admits a G–equivariant structure and the condition that EH admits a (flat) G–connection. The cases of bundles on homogeneous spaces and smooth toric varieties are discussed.
Soit un schéma arithmétique de dimension , c’est-à-dire le spectre de l’anneau des entiers d’un corps de nombres ou une courbe algébrique, lisse, irréductible, définie sur un corps fini ou algébriquement clos. Nous associons à un -espace homogène (à gauche) d’un groupe réductif dont l’isotropie est aussi un groupe réductif une classe caractéristique qui, dans le cas où est semi-simple, vit dans un de à valeurs dans le noyau du revêtement universel d’une -forme de . Cette classe...