Purely infinite C*-algebras from boundary actions of discrete groups.
Quantization commutes with reduction in the non-compact setting: the case of holomorphic discrete series
In this paper we show that the multiplicities of holomorphic discrete series representations relative to reductive subgroups satisfy the credo “quantization commutes with reduction”.
Quantum co-adjoint orbits of the group of affine transformations of the complex line.
Quantum half-planes via deformation quantization.
Quasiconformal groups of compact type.
We establish that a quasiconformal group is of compact type if and only if its limits set is purely conical and find that the limit set of a quasiconformal group of compact type is uniformly perfect. A key tool is the result of Bowditch-Tukia on compact-type convergence groups. These results provide crucial tools for studying the deformations of quasiconformal groups and in establishing isomorphisms between such groups and conformal groups.
Quaternionic and para-quaternionic CR structure on (4n+3)-dimensional manifolds
We define notion of a quaternionic and para-quaternionic CR structure on a (4n+3)-dimensional manifold M as a triple (ω1,ω2,ω3) of 1-forms such that the corresponding 2-forms satisfy some algebraic relations. We associate with such a structure an Einstein metric on M and establish relations between quaternionic CR structures, contact pseudo-metric 3-structures and pseudo-Sasakian 3-structures. Homogeneous examples of (para)-quaternionic CR manifolds are given and a reduction construction of non...
Quotients compacts des groupes ultramétriques de rang un
Soit l’ensemble des points d’un groupe algébrique semi-simple connexe de rang relatif un sur un corps local ultramétrique. Nous décrivons tous les sous-groupes discrets de type fini sans torsion de qui agissent proprement et cocompactement sur par multiplication à gauche et à droite. Nous montrons qu’après une petite déformation dans un tel sous-groupe agit encore librement, proprement discontinûment et cocompactement sur .
Quotients of Coxeter complexes, fundamental groupoids and Regular Graphs.
Rank gradient, cost of groups and the rank versus Heegaard genus problem
We study the growth of the rank of subgroups of finite index in residually finite groups, by relating it to the notion of cost. As a by-product, we show that the ‘rank vs. Heegaard genus’ conjecture on hyperbolic 3-manifolds is incompatible with the ‘fixed price problem’ in topological dynamics.
Rational toral ranks in certain algebras.
Rationalization of Hopf G-Spaces..
Real algebraic actions on projective spaces - A survey
Let be a compact lie group. We introduce the set for every smooth manifold . It consists of equivalence classes of pair where is a map which defines a homotopy equivalence from to . Two pairs , for , are equivalent if there is a homotopy equivalence such that is homotopic to .Properties of the set and related to the representation of on the tangent spaces of and at the fixed points. For the case and is the manifold defined by a “linear” action on complex...
Rechtsdistributive Multiplikationen auf homogenen Räumen.
Regular minimal sets. II : the proximally equicontinuous case
Relations among Invariants of Circle Actions on Three-manifolds.
Relative Invarianten und nicht-assoziative Algebren.
Representation Forms for Metacyclic groups.
Representation of finite groups and the first Betti number of branched coverings of a universal Borromean orbifold
The paper studies the first homology of finite regular branched coverings of a universal Borromean orbifold called B 4,4,4ℍ3. We investigate the irreducible components of the first homology as a representation space of the finite covering transformation group G. This gives information on the first betti number of finite coverings of general 3-manifolds by the universality of B 4,4,4. The main result of the paper is a criterion in terms of the irreducible character whether a given irreducible representation...
Representations of the group of smooth mappings of a manifold X into a compact Lie group
Rigid versus non-rigid cyclic actions.