In this paper, we study the notion of Connes amenability for a class of $I\times{I}$-upper triangular matrix algebra $UP(I,\mathcal{A})$, where $\mathcal{A}$ is a dual Banach algebra with a non-zero $wk^\ast$-continuous character and $I$ is a totally ordered set. For this purpose, we characterize the $ϕ$-Connes amenability of a dual Banach algebra $\mathcal{A}$ through the existence of a specified net in $\mathcal{A}\hat{\otimes}\mathcal{A}$, where $ϕ$ is a non-zero $wk^\ast$-continuous character. Using this, we show that $UP(I,\mathcal{A})$ is Connes amenable if and only if $I$ is singleton and $\mathcal{A}$ is Connes amenable. In addition, some examples of $ϕ$-Connes amenable dual Banach algebras, which is not Connes amenable are given.
Let A be a Banach algebra and I be a closed ideal of A. We say that A is amenable relative to I, if A/I is an amenable Banach algebra. We study the relative amenability of Banach algebras and investigate the relative amenability of triangular Banach algebras and Banach algebras associated to locally compact groups. We generalize some of the previous known results by applying the concept of relative amenability of Banach algebras, especially, we present a generalization of Johnson's theorem in the concept of relative amenability.
In this paper, we introduce a new notion of amenability, $σ-$Connes ideal, say, for a large class of dual Banach algebras. We extend the concept of ideal Connes amenability and study their properties. Let $σ$ be a $weak^{*}$-continuous endomorphism on a dual Banach algebra $\mathcal{A}$ with dense range. Then the concept of ideal Connes-amenability and $σ-$ ideally Connes amenability are the same. We gave some general results and hereditary properties with some examples for this new notion of amenability.
We introduce the notion of Johnson pseudo-Connes amenability for dual Banach algebras. We study the relation between this new notion with the various notions of Connes amenability like Connes amenability, approximate Connes amenability and pseudo Connes amenability. We also investigate some hereditary properties of this new notion. We prove that for a locally compact group $G$, $M(G)$ is Johnson pseudo-Connes amenable if and only if $G$ is amenable. Also we show that for every non-empty set $I$, $\mathbb{M}_I(\mathbb{C})$ under this new notion is forced to have a finite index. Finally, we prov…
We shall develop a notion of amenability for dual Banach algebras, namely weak Connes amenability, which will play the role that weak amenability does for usual Banach algebras
In this paper, we introduce the new notion of strong pseudo-Connes amenability for dual Banach algebras. We study the relation between this new notion to the various notions of Connes amenability. Also we show that for every non-empty set $I$, $M_I(\mathbb{C})$ is strong pseudo-Connes amenable if and only if $I$ is finite. We provide some examples of certain dual Banach algebras and we study its strong pseudo-Connes amenability. In the last section, we investigate the property ultra central approximate identity for a Banach algebra $\mathcal{A}$ and its second dual $\mathcal{A}^{**}$. Also we …
In this paper, we study weak amenability of Beurling algebras. To this end, we introduce the notion inner quasi-additive functions and prove that for a locally compact group $G$, the Banach algebra $L^1(G, ω)$ is weakly amenable if and only if every non-inner quasi-additive function in $L^\infty(G, 1/ω)$ is unbounded. This provides an answer to the question concerning weak amenability of $L^1(G, ω)$ and improve some known results in connection with it.
In this paper, we introduce a notion of approximate Connes-biprojectivity for dual Banach algebras. We study the relation between approximate Connes-biprojectivity, Johnson pseudo-Connes amenability and $φ$-Connes amenability. We propose a criterion to show that some certain dual triangular Banach algebras are not approximately Connes-biprojective. Next we show that for a locally compact group $G$, the Banach algebra $M(G)$ is approximately Connes-biprojective if and only if $G$ is amenable. Finally for an infinite commutative compact group $G$ we show that the Banach algebra $L^2(G)$ with con…
Operator amenability of Fourier-Stieltjes algebras
算子顺从性的概念是由Z. J. Ruan，1995年。他表明，一个局部紧群G是顺从的当且仅当其傅立叶代数A（G）是经营者顺从。本文研究了Fourier-Stieltjes代数B（G）和约化Fourier-Stieltjes代数B_r（G）的算子顺从性。自然的猜想是，这些代数中的任何一个都是算子顺从的当且仅当G是紧的。我们部分地证明了这个猜想与纯粹的运营商顺从性取代运营商C-顺从性，某些常数C < 5。在这个过程中，我们得到了B（G）的一个新的分解，它可以解释为M（G）分解为离散测度和连续测度的非交换对应。我们进一步引入了算子顺从性的一种变体--算子Connes顺从性，它也考虑了B（G）和B_r（G）上的对偶空间结构.证明了B_r（G）是Connes-affected的当且仅当G是affected的.令人惊讶的是，B（F_2）是算子Connes顺从的，尽管两个生成元中的自由群F_2不顺从.
We completely characterize connected Lie groups all of whose countable subgroups are weakly amenable. We also provide a characterization of connected semisimple Lie groups that are weakly amenable. Finally, we show that a connected Lie group is weakly amenable if the group is weakly amenable as a discrete group.
We consider the Fourier-Stietljes algebra B(G) of a locally compact group G. We show that operator amenablility of B(G) implies that a certain semitolpological compactification of G admits only finitely many idempotents. In the case that G is connected, we show that operator amenability of B(G) entails that $G$ is compact.
In this paper, we introduce a new notion of biprojectivity, called $WAP$-biprojectivity for $F(\mathcal{A})$, the enveloping dual Banach algebra associated to a Banach algebra $\mathcal{A}$. We find some relations between Connes biprojectivity, Connes amenability and this new notion. We show that, for a given dual Banach algebra $\mathcal{A}$, if $F(\mathcal{A})$ is Connes amenable, then $\mathcal{A}$ is Connes amenable. For an infinite commutative compact group $G$, we show that the convolution Banach algebra $F(L^2(G))$ is not $WAP$-biprojective. Finally, we provide some examples of the enve…
We study skew-amenable topological groups, i.e., those admitting a left-invariant mean on the space of bounded real-valued functions left-uniformly continuous in the sense of Bourbaki. We prove characterizations of skew-amenability for topological groups of isometries and automorphisms, clarify the connection with extensive amenability of group actions, establish a Følner-type characterization, and discuss closure properties of the class of skew-amenable topological groups. Moreover, we isolate a dynamical sufficient condition for skew-amenability and provide several concrete variations of thi…
Group amenability properties for von Neumann algebras
在他对顺从的酉表示的研究中，M. E. B.贝卡问是否有一个类似的代表性显着的定点财产顺从的群体。在本文中，我们证明了这样一个不动点定理在更一般的背景下的$G$ -顺从冯诺依曼代数$M$，其中$G$是一个局部紧群作用在$M$。本文将Connes和Bekka的Følner条件推广到$M$是半有限的，并且有一个忠实的、半有限的、正规的迹在$G$作用下不变的情形.
We define the notion of self-tracial stability for tracial von Neumann algebras and show that a tracial von Neumann algebra satisfying the Connes Embedding Problem is self-tracially stable if and only if it is amenable. We then generalize a result of Jung by showing that a separable tracial von Neumann algebra that satisfies the Connes Embedding Problem is amenable if and only if any two embeddings into $R^\mathcal{U}$ are ucp-conjugate. Moreover we show that for a II$_1$ factor $N$ satisfying CEP, the space $\mathbb{H}$om$(N, \prod_{k\to \mathcal{U}}M_k)$ of unitary equivalence classes of emb…
Convolutions on compact groups and Fourier algebras of coset spaces
在本说明中，我们研究两个相关的问题。(1)对于紧群G，由$u X v |-> u*v' ($ v '（s）=v（s^{-1}）$) and $ u X v给出的A（G × G）上的卷积映射的值域是什么|-> u*v$？(2)对于一个局部紧群G和一个紧子群K，陪集空间A（G/K）的Fourier代数的顺从性是什么？代数A（G/K）是由第一作者定义和研究的。在回答第一个问题时，我们得到了不允许有限指数交换子群的紧群A（G）的一些新的子代数。利用这些代数，我们可以找到许多情况下，A（G/K）失败的最基本的顺从性质：运营商弱顺从。然而，使用不同的技术，我们证明了，如果G的单位元的连通分支是阿贝尔，那么A（G/K）总是满足更强的性质，它是超Tauberian，这是一个概念，由第二命名的作者。我们还建立了一类包含最大概周期群的群A（G/K）的算子顺从性的准则。
