Relative amenability

We introduce a relative fixed point property for subgroups of a locally compact group, which we call relative amenability. It is a priori weaker than amenability. We establish equivalent conditions, related among others to a problem studied by Reiter in 1968. We record a solution to Reiter's problem. We study the class X of groups in which relative amenability is equivalent to amenability for all closed subgroups; we prove that X contains all familiar groups. Actually, no group is known to lie outside X. Since relative amenability is closed under Chabauty limits, it follows that any Chabauty limit of amenable subgroups remains amenable if the ambient group belongs to the vast class X.


Published in:
Groups Geometry And Dynamics, 8, 3, 747-774
Year:
2014
Publisher:
Zurich, European Mathematical Soc
ISSN:
1661-7207
Keywords:
Laboratories:




 Record created 2015-02-20, last modified 2018-01-28


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