Isolated fixed points of circle actions on 4-manifolds.
Jacobi actions of and on two Jacobi manifolds.
Kazhdan constants for SL (3, Z).
Klein Hyperbottle
Knots Fixed by Zp-Actions and Periodic Links.
Large group actions on manifolds.
Lattices in semisimple groups and distal geometric structures.
Les groupes hyperboliques
Lie group structures on groups of diffeomorphisms and applications to CR manifolds
We give general sufficient conditions to guarantee that a given subgroup of the group of diffeomorphisms of a smooth or real-analytic manifold has a compatible Lie group structure. These results, together with recent work concerning jet parametrization and complete systems for CR automorphisms, are then applied to determine when the global CR automorphism group of a CR manifold is a Lie group in an appropriate topology.
Local Classification of Quotients of Smooth Manifolds by Discontinuous Groups.
Local Groups of Differentiable Transformations.
Local properties of stably complex -actions
Local rigidity of discrete groups acting on complex hyperbolic space.
Local Surgery Obstructions and Space Forms.
Lokale Klassifikation von Quotientensingularitäten reeller Mannigfaltigkeiten nach diskreten Gruppen.
Lorentzian similarity manifolds
An (m+2)-dimensional Lorentzian similarity manifold M is an affine flat manifold locally modeled on (G,ℝm+2), where G = ℝm+2 ⋊ (O(m+1, 1)×ℝ+). M is also a conformally flat Lorentzian manifold because G is isomorphic to the stabilizer of the Lorentzian group PO(m+2, 2) of the Lorentz model S m+1,1. We discuss the properties of compact Lorentzian similarity manifolds using developing maps and holonomy representations.
Maximal Hamiltonian tori for polygon spaces
We study the poset of Hamiltonian tori for polygon spaces. We determine some maximal elements and give examples where maximal Hamiltonian tori are not all of the same dimension.
Measured foliations and mapping class groups of surfaces.
Minimality and unique ergodicity for subgroup actions
Let be an -algebraic semisimple group, an algebraic -subgroup, and a lattice in . Partially answering a question posed by Hillel Furstenberg in 1972, we prove that if the action of on is minimal, then it is uniquely ergodic. Our proof uses in an essential way Marina Ratner’s classification of probability measures on invariant under unipotent elements, and the study of “tubes” in .
Mod 2 Semi-characteristics and the Converse to a Theorem of Milnor.