Actions of compact connected Lie groups on acyclic manifolds with low dimensional orbit spaces.
Actions of Compact Lie Groups on Homogeneous Spaces.
Actions of Groups with Periodic Cohomology on Poincaré Duality Spaces.
Actions of some infinite Lie groups.
Actions of the group of homeomorphisms of the circle on surfaces
We describe all the group morphisms from the group of orientation-preserving homeomorphisms of the circle to the group of homeomorphisms of the annulus or of the torus.
Actions of the Homeotopy Group of an Orientable 3-Dimensional Handle Body.
Actions of on some surface-bundles over
Adhérence d'orbite et invariants.
Affine Actions of Higher Rank Lattices.
Affine group acting on hyperspaces of compact convex subsets of ℝⁿ
For every n ≥ 2, let cc(ℝⁿ) denote the hyperspace of all nonempty compact convex subsets of the Euclidean space ℝⁿ endowed with the Hausdorff metric topology. Let cb(ℝⁿ) be the subset of cc(ℝⁿ) consisting of all compact convex bodies. In this paper we discover several fundamental properties of the natural action of the affine group Aff(n) on cb(ℝⁿ). We prove that the space E(n) of all n-dimensional ellipsoids is an Aff(n)-equivariant retract of cb(ℝⁿ). This is applied to show that cb(ℝⁿ) is homeomorphic...
Aktionen kompakter Liegruppen auf lokalen Räumen.
Algebraic Hulls and the Folner Property.
Algebraic Transformation Groups and Representation.
Allgemeine Lage und äquivariante Homotopie.
Almost complex toric manifolds and positive line bundles
Almost invariant submanifolds for compact group actions
We define a distance between submanifolds of a riemannian manifold and show that, if a compact submanifold is not moved too much under the isometric action of a compact group , there is a -invariant submanifold -close to . The proof involves a procedure of averaging nearby submanifolds of riemannian manifolds in a symmetric way. The procedure combines averaging techniques of Cartan, Grove/Karcher, and de la Harpe/Karoubi with Whitney’s idea of realizing submanifolds as zeros of sections...
Almost transitive actions on spaces with the rational homotopy of sphere products.
Almost-Bieberbach groups with prime order holonomy
The main issue of this paper is an attempt to find a decomposition theorem for infra-nilmanifolds in the same spirit as a result of A. Vasquez for flat Riemannian manifolds. That is: we look for infra-nilmanifolds with prime order holonomy which can be obtained as a fiber space with a non-trivial nilmanifold as fiber and an infra-nilmanifold as its base. In this perspective, we prove the following algebraic result: if E is an almost-Bieberbach group with prime order holonomy,...
Amenable hyperbolic groups
We give a complete characterization of the locally compact groups that are non elementary Gromov-hyperbolic and amenable. They coincide with the class of mapping tori of discrete or continuous one-parameter groups of compacting automorphisms. We moreover give a description of all Gromov-hyperbolic locally compact groups with a cocompact amenable subgroup: modulo a compact normal subgroup, these turn out to be either rank one simple Lie groups, or automorphism groups of semiregular trees acting doubly...
An algebraic group associated to an ergodic diffeomorphism