Do you want to publish a course? Click here

Amenable uniformly recurrent subgroups and lattice embeddings

42   0   0.0 ( 0 )
 Added by Adrien Le Boudec
 Publication date 2018
  fields
and research's language is English




Ask ChatGPT about the research

We study lattice embeddings for the class of countable groups $Gamma$ defined by the property that the largest amenable uniformly recurrent subgroup $A_Gamma$ is continuous. When $A_Gamma$ comes from an extremely proximal action and the envelope of $A_Gamma$ is co-amenable in $Gamma$, we obtain restrictions on the locally compact groups $G$ that contain a copy of $Gamma$ as a lattice, notably regarding normal subgroups of $G$, product decompositions of $G$, and more generally dense mappings from $G$ to a product of locally compact groups.



rate research

Read More

71 - Jared T. White 2020
Let $G$ be an amenable group. We define and study an algebra $mathcal{A}_{sn}(G)$, which is related to invariant means on the subnormal subgroups of $G$. For a just infinite amenable group $G$, we show that $mathcal{A}_{sn}(G)$ is nilpotent if and only if $G$ is not a branch group, and in the case that it is nilpotent we determine the index of nilpotence. We next study $operatorname{rad} ell^1(G)^{**}$ for an amenable branch group $G$, and show that it always contains nilpotent left ideals of arbitrarily large index, as well as non-nilpotent elements. This provides infinitely many finitely-generated counterexamples to a question of Dales and Lau, first resolved by the author in a previous article, which asks whether we always have $(operatorname{rad} ell^1(G)^{**})^{Box 2} = { 0 }$. We further study this question by showing that $(operatorname{rad} ell^1(G)^{**})^{Box 2} = { 0 }$ imposes certain structural constraints on the group $G$.
The goal of this article is to study results and examples concerning finitely presented covers of finitely generated amenable groups. We collect examples of groups $G$ with the following properties: (i) $G$ is finitely generated, (ii) $G$ is amenable, e.g. of intermediate growth, (iii) any finitely presented group $E$ with a quotient isomorphic to $G$ contains non-abelian free subgroups, or the stronger (iii) any finitely presented group with a quotient isomorphic to $G$ is large.
404 - Aditi Kar , Graham A. Niblo 2010
We generalize a result of R. Thomas to establish the non-vanishing of the first l2-Betti number for a class of finitely generated groups.
We show that topological amenability of an action of a countable discrete group on a compact space is equivalent to the existence of an invariant mean for the action. We prove also that this is equivalent to vanishing of bounded cohomology for a class of Banach G-modules associated to the action, as well as to vanishing of a specific cohomology class. In the case when the compact space is a point our result reduces to a classic theorem of B.E. Johnson characterising amenability of groups. In the case when the compact space is the Stone-v{C}ech compactification of the group we obtain a cohomological characterisation of exactness for the group, answering a question of Higson.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا