INVARIANT EXPECTATIONS AND VANISHING OF BOUNDED COHOMOLOGY FOR EXACT GROUPS

被引:4
作者
Douglas, Ronald G. [1 ]
Nowak, Piotr W. [1 ]
机构
[1] Texas A&M Univ, Dept Math, College Stn, TX 77843 USA
基金
美国国家科学基金会;
关键词
Exact group; bounded cohomology; Hochschild cohomology; convolution algebra; invariant expectation; CONTINUOUS BUNDLES; SPACES;
D O I
10.1142/S1793525311000489
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
We study exactness of groups and establish a characterization of exact groups in terms of the existence of a continuous linear operator, called an invariant expectation, whose properties make it a weak counterpart of an invariant mean on a group. We apply this operator to show that exactness of a finitely generated group G implies the vanishing of the bounded cohomology of G with coefficients in a new class of modules, which are defined using the Hopf algebra structure of l(1)(G).
引用
收藏
页码:89 / 107
页数:19
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