搜索结果: 1-15 共查到“数学 actions”相关记录57条 . 查询时间(0.249 秒)
CONFORMAL ACTIONS OF NILPOTENT GROUPS ON PSEUDO-RIEMANNIAN MANIFOLDS
CONFORMAL ACTIONS PSEUDO-RIEMANNIAN MANIFOLDS
2015/10/14
We study conformal actions of connected nilpotent Lie groups
on compact pseudo-Riemannian manifolds. We prove that if a type-(p,q)
compact manifold M supports a conformal action of a connected nilpo...
Isometric actions of Heisenberg groups on compact Lorentz manifolds
Heisenberg groupsl Lorentz manifolds
2015/10/14
We prove results toward classifying compact Lorentz manifolds on
which Heisenberg groups act isometrically. We give a general construction,
leading to a new example, of codimension-one actions—those...
ERGODICITY OF MAPPING CLASS GROUP ACTIONS ON SU(2)-CHARACTER VAR IET IES
GROUP ACTIONS MAPPING CLASS
2015/9/29
Let be a compact orientable surface with genus g andnboundary components
∂1,..., ∂n. Let b = (b1,...,bn) ∈ [−2,2]
n. Then the mapping class group
Mod() acts on the relative SU(2)-...
Proper affine actions and geodesic flows of hyperbolic surfaces
hyperbolic surfaces geodesic fl ows
2015/9/29
Let €0 O.2; 1/ be a Schottky group, and let † D H
2=€0 be the corresponding
hyperbolic surface. Let C.†/ denote the space of unit length geodesic currents
on †. The cohom...
The Margulis Invariant of Isometric Actions on Minkowski (2+1)-Space
Minkowski (2+1)-Space Isometric Actions
2015/9/29
Let E denote an a±ne space modelled on Minkowski (2+1)-space E
and let ¡ be a group of isometries whose linear part L(¡) is a purely hyperbolic
subgroup of SO0
(2;1). Margulis has deˉned ...
Symplectic 4-manifolds with fixed point free circle actions
Symplectic 4-manifolds point free circle actions Geometric Topology
2012/6/19
We show that recent results of Friedl-Vidussi and Chen imply that a symplectic manifold admits a fixed point free circle action if and only if it admits a symplectic circle action and we give a comple...
We exhibit sufficient conditions for a monoidal monad T on a monoidal category C to induce a monoidal structure on the Eilenberg--Moore category C^T that classifies bimorphisms. The category of action...
A characterization of amenability of group actions on $C^\ast$-algebras
characterization amenability group actions $C^\ast$-algebras
2012/4/16
We show that coincidence of the full and reduced crossed product $C^\ast$-algebras of a group action on a unital commutative $C^\ast$-algebra implies amenability of the action whenever the group is ex...
Finite generators for countable group actions in the Borel and Baire category settings
Finite generators countable group actions Baire category settings Logic
2012/4/23
For a countable group G and a standard Borel G-space X, a countable Borel partition P of X is called a generator if {gA : g in G, A in P} generates the Borel sigma-algebra of X. For G=Z, the Kolmogoro...
Amenable, transitive and faithful actions of groups acting on trees
Amenable transitive faithful actions groups trees
2012/3/1
We study under which condition an amalgamated free product or an HNN-extension over a finite subgroup admits an amenable, transitive and faithful action on an infinite countable set. We show that such...
Higher cohomology for Anosov actions on certain homogeneous spaces
Higher cohomology Anosov actions certain homogeneous spaces
2011/9/19
Abstract: We study the smooth untwisted cohomology with real coefficients for the action on [SL(2, R) \times \cdot \cdot \cdot \times SL(2, R)]/{\Gamma} by the subgroup of diagonal matrices, where {\G...
Actions and identities on set partitions
Actions and identities set partitions Combinatorics
2011/9/16
Abstract: A labeled set partition is a partition of a set of integers whose arcs are labeled by nonzero elements of an abelian group $A$. Inspired by the action of the linear characters of the unitria...
Abstract: In this paper we introduce the definition of partial action on small $k$-categories generalizing the similar well known notion of partial actions on algebras. The point of view of partial ac...
A Lower Bound for the Number of Group Actions on a Compact Riemann Surface
Riemann surface automorphism signature mapping class group
2011/9/14
Abstract: We prove that the number of distinct group actions on compact Riemann surfaces of a fixed genus $\sigma \geq 2$ is at least quadratic in $\sigma$. We do this through the introduction of a co...
Optimal paths for symmetric actions in the unitary group
geodesic segment Lagrangian optimal path unitarily invariant norm unitary group Grassmann manifold angular metric
2011/9/5
Abstract: Given a positive and unitarily invariant Lagrangian L defined in the algebra of Hermitian matrices, and a fixed interval $[a,b]\subset\mathbb R$, we study the action defined in the Lie group...