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On a co-induction question of Kechris

Group Theory 2011-08-03 v3 Dynamical Systems

Abstract

This note answers a question of Kechris: if H<GH<G is a normal subgroup of a countable group GG, HH has property MD and G/HG/H is amenable and residually finite then GG also has property MD. Under the same hypothesis we prove that for any action aa of GG, if bb is a free action of G/HG/H, and bGb_G is the induced action of GG then \CIndHG(aH)×bG\CInd_H^G(a|H) \times b_G weakly contains aa. Moreover, if H<GH<G is any subgroup of a countable group GG, and the action of GG on G/HG/H is amenable, then \CIndHG(aH)\CInd_H^G(a|H) weakly contains aa whenever aa is a Gaussian action.

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Cite

@article{arxiv.1105.0648,
  title  = {On a co-induction question of Kechris},
  author = {Lewis Bowen and Robin Tucker-Drob},
  journal= {arXiv preprint arXiv:1105.0648},
  year   = {2011}
}

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