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SUMMARY:Minicourse: topological full groups (1) - Hiroki  Matui (Chiba Uni
 versity)
DTSTART:20250630T150000Z
DTEND:20250630T163000Z
UID:TALK233155@talks.cam.ac.uk
DESCRIPTION:In this mini-course\, we will introduce various properties and
  examples of topological full groups\, which are discrete groups naturally
  associated with etale groupoids whose unit spaces are Cantor sets. Over t
 he past two decades\, these groups have been extensively studied and are n
 ow known to exhibit a rich array of features\, such as simplicity\, amenab
 ility\, and finite generation\, making them central objects at the interse
 ction of group theory\, topology\, and operator algebras.&nbsp\;Starting f
 rom the definition of topological full groups\, we will discuss basic exam
 ples arising from minimal Z-actions and AF groupoids. We will also explain
  the connections to groupoid homology\, and the reconstruction theorem whi
 ch claims the group structure of the topological full group remembers the 
 groupoid itself.A significant part of the theory revolves around the dicho
 tomy of ample groupoids into two classes: almost finite and purely infinit
 e groupoids. With this distinction in mind\, we will discuss structural re
 sults such as simplicity of the commutator subgroup\, amenability\, and fi
 nite generation of topological full groups. Depending on time constraints\
 , we may select certain topics to discuss in more detail.&nbsp\;\nFuther p
 repartory reading (this will not be assumed)\nSection 2: Preliminaries of 
 the paper: X. Li\, &rdquo\;Ample groupoids\, topological full groups\, alg
 ebraic K-theory spectra and infinite loop spaces\,&rdquo\; Forum Math. Pi 
 13 (2025)\, (available at arXiv:2209.08087).\nH. Matui\, &rdquo\;Topologic
 al full groups of etale groupoids\,&rdquo\; in Operator Algebras and Appli
 cations&mdash\;The Abel Symposium 2015\, Abel Symp. 12\, Springer\, 2016\,
  (available at arXiv:1602.00383)
LOCATION:External
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