Følner Nets for Semidirect Products of Amenable Groups

2008 ◽  
Vol 51 (1) ◽  
pp. 60-66 ◽  
Author(s):  
David Janzen
Keyword(s):  
Strong Form ◽  
Locally Compact ◽  
Amenable Groups ◽  
Semidirect Products ◽  
Euclidean Motion ◽  
Motion Groups

AbstractFor unimodular semidirect products of locally compact amenable groups N and H, we show that one can always construct a Følner net of the form (Aα × Bβ) for G, where (Aα) is a strong form of Følner net for N and (Bβ) is any Følner net for H. Applications to the Heisenberg and Euclidean motion groups are provided.

Topological Left Amenability of Semidirect Products

1981 ◽  
Vol 24 (1) ◽  
pp. 79-85 ◽  
Author(s):  
H. D. Junghenn
Keyword(s):  
Large Class ◽  
Semidirect Product ◽  
Locally Compact ◽  
Semidirect Products ◽  
Topological Semigroups

AbstractLet S and T be locally compact topological semigroups and a semidirect product. Conditions are determined under which topological left amenability of S and T implies that of , and conversely. The results are used to show that for a large class of semigroups which are neither compact nor groups, various notions of topological left amenability coincide.

Variants of stability of discontinuous groups for Euclidean motion groups

2017 ◽  
Vol 28 (06) ◽  
pp. 1750046 ◽  
Author(s):  
Ali Baklouti ◽  
Souhail Bejar
Keyword(s):  
Lie Group ◽  
Closed Subgroup ◽  
Deformation Parameter ◽  
Motion Group ◽  
Discontinuous Group ◽  
Euclidean Motion Group ◽  
Euclidean Motion ◽  
Motion Groups ◽  
Discontinuous Groups ◽  
Properly Discontinuous Action

Let [Formula: see text] be a Lie group, [Formula: see text] a closed subgroup of [Formula: see text] and [Formula: see text] a discontinuous group for the homogeneous space [Formula: see text]. Given a deformation parameter [Formula: see text], the deformed subgroup [Formula: see text] may fail to act properly discontinuously on [Formula: see text]. To understand this phenomenon in the case when [Formula: see text] stands for an Euclidean motion group [Formula: see text], we compare the notion of stability for discontinuous groups (cf. [T. Kobayashi and S. Nasrin, Deformation of properly discontinuous action of [Formula: see text] on [Formula: see text], Int. J. Math. 17 (2006) 1175–1193]) with its variants. We prove that the defined stability variants hold when [Formula: see text] turns out to be a crystallographic subgroup of [Formula: see text].

Uniformly Continuous Functionals and M-Weakly Amenable Groups

2013 ◽  
Vol 65 (5) ◽  
pp. 1005-1019 ◽  
Author(s):  
Brian Forrest ◽  
Tianxuan Miao
Keyword(s):  
Compact Group ◽  
Amenable Group ◽  
Locally Compact Group ◽  
Approximate Identity ◽  
Fourier Algebra ◽  
Locally Compact ◽  
Amenable Groups ◽  
Invariant Means ◽  
Continuous Functionals ◽  
Uniformly Continuous

AbstractLet G be a locally compact group. Let AM(G) (A0(G))denote the closure of A(G), the Fourier algebra of G in the space of bounded (completely bounded) multipliers of A(G). We call a locally compact group M-weakly amenable if AM(G) has a bounded approximate identity. We will show that when G is M-weakly amenable, the algebras AM(G) and A0(G) have properties that are characteristic of the Fourier algebra of an amenable group. Along the way we show that the sets of topologically invariant means associated with these algebras have the same cardinality as those of the Fourier algebra.

scholarly journals APPROXIMATION PROPERTIES FOR CROSSED PRODUCTS BY ACTIONS AND COACTIONS

2001 ◽  
Vol 12 (05) ◽  
pp. 595-608 ◽  
Author(s):  
MAY M. NILSEN ◽  
ROGER R. SMITH
Keyword(s):  
Approximation Property ◽  
Locally Compact Groups ◽  
Compact Groups ◽  
Crossed Products ◽  
Approximation Properties ◽  
Locally Compact ◽  
Amenable Groups ◽  
C Algebras ◽  
Approximation Constant

We investigate approximation properties for C*-algebras and their crossed products by actions and coactions by locally compact groups. We show that Haagerup's approximation constant is preserved for crossed products by arbitrary amenable groups, and we show why this is not always true in the non-amenable case. We also examine similar questions for other forms of the approximation property.

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