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SUMMARY:François Le Maître (Université de Paris)
DTSTART:20210125T073000Z
DTEND:20210125T083000Z
DTSTAMP:20260423T021353Z
UID:SiN/12
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/SiN/12/">Den
 se totipotent free subgroups of full groups</a>\nby François Le Maître (
 Université de Paris) as part of Symmetry in Newcastle\n\n\nAbstract\nIn t
 his talk\, we will be interested in measure-preserving actions of countabl
 e groups on standard probability spaces\, and more precisely in the partit
 ions of the space into orbits that they induce\, also called measure-prese
 rving equivalence relations. In 2000\, Gaboriau obtained a characterizatio
 n of the ergodic equivalence relations which come from non-free actions of
  the free group on $n > 1$ generators: these are exactly the equivalence r
 elations of cost less than n. A natural question is: how non-free can thes
 e actions be made\, and what does the action on each orbit look like? We w
 ill obtain a satisfactory answer by showing that the action on each orbit 
 can be made totipotent\, which roughly means "as rich as possible"\, and f
 urthermore that the free group can be made dense in the ambient full group
  of the equivalence relation.\n\nThis is joint work with Alessandro Carder
 i and Damien Gaboriau.\n
LOCATION:https://researchseminars.org/talk/SiN/12/
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