scholarly journals Covariant functions of characters of compact subgroups

2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Arash Ghaani Farashahi
Keyword(s):  
Compact Group ◽  
Harmonic Analysis ◽  
Banach Spaces ◽  
Systematic Study ◽  
Dual Space ◽  
Quotient Space ◽  
Compact Subgroup ◽  
Locally Compact Group ◽  
Locally Compact ◽  
Conjugate Exponent

AbstractThis paper presents a systematic study for abstract harmonic analysis on classical Banach spaces of covariant functions of characters of compact subgroups. Let G be a locally compact group and H be a compact subgroup of G. Suppose that $$\xi :H\rightarrow \mathbb {T}$$ ξ : H → T is a character, $$1\le p<\infty$$ 1 ≤ p < ∞ and $$L_\xi ^p(G,H)$$ L ξ p ( G , H ) is the set of all covariant functions of $$\xi$$ ξ in $$L^p(G)$$ L p ( G ) . It is shown that $$L^p_\xi (G,H)$$ L ξ p ( G , H ) is isometrically isomorphic to a quotient space of $$L^p(G)$$ L p ( G ) . It is also proven that $$L^q_\xi (G,H)$$ L ξ q ( G , H ) is isometrically isomorphic to the dual space $$L^p_\xi (G,H)^*$$ L ξ p ( G , H ) ∗ , where q is the conjugate exponent of p. The paper is concluded by some results for the case that G is compact.

scholarly journals ON HOMOLOGICAL PROPERTIES FOR SOME MODULES OF UNIFORMLY CONTINUOUS FUNCTIONS OVER CONVOLUTION ALGEBRAS

2011 ◽  
Vol 84 (2) ◽  
pp. 177-185
Author(s):  
RASOUL NASR-ISFAHANI ◽  
SIMA SOLTANI RENANI
Keyword(s):  
Compact Group ◽  
Group Algebra ◽  
Dual Space ◽  
Continuous Functions ◽  
Locally Compact Group ◽  
Measure Algebra ◽  
Locally Compact ◽  
Convolution Algebras ◽  
Uniformly Continuous

AbstractFor a locally compact group G, let LUC(G) denote the space of all left uniformly continuous functions on G. Here, we investigate projectivity, injectivity and flatness of LUC(G) and its dual space LUC(G)* as Banach left modules over the group algebra as well as the measure algebra of G.

scholarly journals On a Certain Class of Semigroups of Operators

2011 ◽  
Vol 18 (02) ◽  
pp. 129-142 ◽  
Author(s):  
Paolo Aniello
Keyword(s):  
Banach Space ◽  
Compact Group ◽  
Banach Spaces ◽  
Locally Compact Group ◽  
Semigroups Of Operators ◽  
Probability Measures ◽  
Locally Compact ◽  
Quantum Dynamical ◽  
Interesting Class ◽  
Natural Way

We define an interesting class of semigroups of operators in Banach spaces, namely, the randomly generated semigroups. This class contains as a remarkable subclass a special type of quantum dynamical semigroups introduced in the early 1970s by Kossakowski. Each randomly generated semigroup is associated, in a natural way, with a pair formed by a representation or an antirepresentation of a locally compact group in a Banach space and by a convolution semigroup of probability measures on this group. Examples of randomly generated semigroups having important applications in physics are briefly illustrated.

SOME HOMOLOGICAL PROPERTIES OF FOURIER ALGEBRAS ON HOMOGENEOUS SPACES

2020 ◽  
pp. 1-9
Author(s):  
REZA ESMAILVANDI ◽  
MEHDI NEMATI
Keyword(s):  
Compact Group ◽  
Homogeneous Space ◽  
Homogeneous Spaces ◽  
Compact Subgroup ◽  
Locally Compact Group ◽  
Fourier Algebra ◽  
Locally Compact ◽  
Weakly Compact

Abstract Let $ H $ be a compact subgroup of a locally compact group $ G $ . We first investigate some (operator) (co)homological properties of the Fourier algebra $A(G/H)$ of the homogeneous space $G/H$ such as (operator) approximate biprojectivity and pseudo-contractibility. In particular, we show that $ A(G/H) $ is operator approximately biprojective if and only if $ G/H $ is discrete. We also show that $A(G/H)^{**}$ is boundedly approximately amenable if and only if G is compact and H is open. Finally, we consider the question of existence of weakly compact multipliers on $A(G/H)$ .

The Von Neumann Algebra VN(G) of a Locally Compact Group and Quotients of Its Subspaces

1997 ◽  
Vol 49 (6) ◽  
pp. 1117-1138
Author(s):  
Zhiguo Hu
Keyword(s):  
Compact Group ◽  
Von Neumann Algebra ◽  
Quotient Space ◽  
Linear Mapping ◽  
Locally Compact Group ◽  
Continuous Linear ◽  
Locally Compact ◽  
Von Neumann ◽  
Quotient Spaces ◽  
Invariant Means

AbstractLet VN(G) be the von Neumann algebra of a locally compact group G. We denote by μ the initial ordinal with |μ| equal to the smallest cardinality of an open basis at the unit of G and X = ﹛α ; α < μ﹜.We show that if G is nondiscrete then there exist an isometric *-isomorphism of l∞(X) into VN(G) and a positive linear mapping π of VN(G) onto l∞(X) such that π o = idl∞(X) and and π have certain additional properties. Let UCB((Ĝ)) be the C*–algebra generated by operators in VN(G) with compact support and F(Ĝ) the space of all T∈ VN(G) such that all topologically invariant means on VN(G) attain the same value at T. The construction of the mapping π leads to the conclusion that the quotient space UCB((Ĝ))/F((Ĝ)) ∪UCB((Ĝ)) has l∞(X) as a continuous linear image if G is nondiscrete. When G is further assumed to be non-metrizable, it is shown that UCB((Ĝ))/F((Ĝ)) ∪UCB((Ĝ)) contains a linear isomorphic copy of l∞(X). Similar results are also obtained for other quotient spaces.

Feichtinger's Segal algebra on homogeneous spaces

2015 ◽  
Vol 26 (08) ◽  
pp. 1550054 ◽  
Author(s):  
K. Parthasarathy ◽  
N. Shravan Kumar
Keyword(s):  
Compact Group ◽  
Homogeneous Spaces ◽  
Compact Subgroup ◽  
Locally Compact Group ◽  
Locally Compact ◽  
Segal Algebra ◽  
Definition Of

Let K be a compact subgroup of a locally compact group G. We extend to the context of homogeneous spaces, G/K, the definition of Feichtinger's Segal algebra. The functorial properties of the Segal algebra are proved.

scholarly journals Harmonic analysis on the Fourier algebras A1, p(G)

1981 ◽  
Vol 30 (4) ◽  
pp. 438-452 ◽  
Author(s):  
Hang-Chin Lai ◽  
Ing-Sheun Chen
Keyword(s):  
Compact Group ◽  
Harmonic Analysis ◽  
Locally Compact Group ◽  
Fourier Algebra ◽  
Locally Compact

AbstractLet G be a locally compact group G (which may be non-abelian) and Ap(G) the p-Fourier algebra of Herz (1971). This paper is concerned with the Fourier algebra Al, p(G) = Ap(G) ∩ L1(G) and various relations that exist between Al, p(G), Ap(G) and G.

scholarly journals ON THE TOPOLOGICAL CENTRE OF L1(G/H)**

2012 ◽  
Vol 86 (1) ◽  
pp. 119-125 ◽  
Author(s):  
R. RAISI TOUSI ◽  
R. A. KAMYABI-GOL ◽  
H. R. EBRAHIMI VISHKI
Keyword(s):  
Compact Group ◽  
Banach Algebras ◽  
Compact Subgroup ◽  
Locally Compact Group ◽  
Locally Compact Groups ◽  
Compact Groups ◽  
General Criterion ◽  
Unified Approach ◽  
Locally Compact ◽  
Topological Centre

AbstractLet G be a locally compact group and H be a compact subgroup of G. Using a general criterion established by Neufang [‘A unified approach to the topological centre problem for certain Banach algebras arising in abstract harmonic analysis’, Arch. Math.82(2) (2004), 164–171], we show that the Banach algebra L1(G/H) is strongly Arens irregular for a large class of locally compact groups.

scholarly journals Extreme non-Arens regularity of the group algebra

2018 ◽  
Vol 30 (5) ◽  
pp. 1193-1208
Author(s):  
Mahmoud Filali ◽  
Jorge Galindo
Keyword(s):  
Compact Group ◽  
Quotient Space ◽  
Closed Subspace ◽  
Banach Algebras ◽  
Locally Compact Group ◽  
Linear Isometry ◽  
Locally Compact ◽  
Convolution Algebra ◽  
Arens Regularity ◽  
Bounded Functions

AbstractThe Banach algebras of Harmonic Analysis are usually far from being Arens regular and often turn out to be as irregular as possible. This utmost irregularity has been studied by means of two notions: strong Arens irregularity, in the sense of Dales and Lau, and extreme non-Arens regularity, in the sense of Granirer. Lau and Losert proved in 1988 that the convolution algebra {L^{1}(G)} is strongly Arens irregular for any infinite locally compact group. In the present paper, we prove that {L^{1}(G)} is extremely non-Arens regular for any infinite locally compact group. We actually prove the stronger result that for any non-discrete locally compact group G, there is a linear isometry from {L^{\infty}(G)} into the quotient space {L^{\infty}(G)/\mathcal{F}(G)}, with {\mathcal{F}(G)} being any closed subspace of {L^{\infty}(G)} made of continuous bounded functions. This, together with the known fact that {\ell^{\infty}(G)/\mathscr{W\!A\!P}(G)} always contains a linearly isometric copy of {\ell^{\infty}(G)}, proves that {L^{1}(G)} is extremely non-Arens regular for every infinite locally compact group.

scholarly journals The predual of the space of convolutors on a locally compact group

1998 ◽  
Vol 57 (3) ◽  
pp. 409-414 ◽  
Author(s):  
Michael Cowling
Keyword(s):  
Compact Group ◽  
Maximal Ideal ◽  
Lebesgue Space ◽  
Dual Space ◽  
Locally Compact Group ◽  
Ideal Space ◽  
Convolution Operators ◽  
Locally Compact ◽  
Algebra Of Functions ◽  
Definition Of

Let Cvp(G) be the space of convolution operators on the Lebesgue space LP(G), for an arbitrary locally compact group G. We describe Cvp(G) as a dual space, whose predual, is a Banach algebra of functions on G, under pointwise operations, with maximal ideal space G. This involves a variation of Herz's definition of AP(G); the benefit of this new definition is that all of Cvp(G) is obtained as the dual in the nonamenable setting. We also discuss further developments of this idea.

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