New algebras of functions on topological groups arising from G-spaces

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Main Authors: Glasner, Eli, Megrelishvili, Michael
Format: Preprint
Published: 2006
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author Glasner, Eli
Megrelishvili, Michael
author_facet Glasner, Eli
Megrelishvili, Michael
contents For a topological group G we introduce the algebra SUC(G) of strongly uniformly continuous functions. It contains the algebra WAP(G) of weakly almost periodic functions as well as the algebras LE(G) and Asp(G) of locally equicontinuous and Asplund functions respectively. For the Polish groups of order preserving homeomorphisms of the unit interval and of isometries of the Urysohn space of diameter 1, SUC(G) is trivial. We study the Roelcke algebra (= UC(G) = right and left uniformly continuous functions) and SUC compactifications of the groups S(N), of permutations of a countable set, and H(C), the group of homeomorphisms of the Cantor set. For the first group we show that WAP(G)=SUC(G)=UC(G) and also provide a concrete description of the corresponding metrizable (in fact Cantor) semitopological semigroup compactification. For the second group, in contrast, we show that SUC(G) is properly contained in UC(G) and for this group UC(G) does not yield a right topological semigroup compactification. We introduce the notion of fixed point on a class P of flows (P-fpp) and study in particular groups which are SUC-amenable and groups with the SUC-fpp (SUC-extreme amenability). We show that every Polish group G with metrizable M(G) is SUC-amenable and if, in addition, M(G) is proximal, then G is SUC-extremely amenable.
format Preprint
id arxiv_https___arxiv_org_abs_math_0608575
institution arXiv
publishDate 2006
record_format arxiv
spellingShingle New algebras of functions on topological groups arising from G-spaces
Glasner, Eli
Megrelishvili, Michael
Dynamical Systems
General Topology
54H20, 22F05, 37C20
For a topological group G we introduce the algebra SUC(G) of strongly uniformly continuous functions. It contains the algebra WAP(G) of weakly almost periodic functions as well as the algebras LE(G) and Asp(G) of locally equicontinuous and Asplund functions respectively. For the Polish groups of order preserving homeomorphisms of the unit interval and of isometries of the Urysohn space of diameter 1, SUC(G) is trivial. We study the Roelcke algebra (= UC(G) = right and left uniformly continuous functions) and SUC compactifications of the groups S(N), of permutations of a countable set, and H(C), the group of homeomorphisms of the Cantor set. For the first group we show that WAP(G)=SUC(G)=UC(G) and also provide a concrete description of the corresponding metrizable (in fact Cantor) semitopological semigroup compactification. For the second group, in contrast, we show that SUC(G) is properly contained in UC(G) and for this group UC(G) does not yield a right topological semigroup compactification. We introduce the notion of fixed point on a class P of flows (P-fpp) and study in particular groups which are SUC-amenable and groups with the SUC-fpp (SUC-extreme amenability). We show that every Polish group G with metrizable M(G) is SUC-amenable and if, in addition, M(G) is proximal, then G is SUC-extremely amenable.
title New algebras of functions on topological groups arising from G-spaces
topic Dynamical Systems
General Topology
54H20, 22F05, 37C20
url https://arxiv.org/abs/math/0608575