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SUMMARY:Kim Ruane (Tufts University)
DTSTART:20220113T150500Z
DTEND:20220113T155500Z
DTSTAMP:20260423T035414Z
UID:GaTO/50
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/GaTO/50/">To
 rsion-free groups acting geometrically on the product of two trees</a>\nby
  Kim Ruane (Tufts University) as part of Geometry and topology online\n\n\
 nAbstract\nGiven a group acting geometrically on product of two trees\, we
  know that one visual boundary is the topological join of two Cantor sets.
   We prove that these groups are "boundary rigid": any CAT(0) space on whi
 ch the group acts has visual boundary homeomorphic to such a join. \n \nSi
 nce there is no hyperbolicity going on here\, one cannot expect that the n
 atural equivariant quasi-isometry between an arbitrary CAT(0) space and th
 e product of two trees to extend to any sort of map on boundaries\, thus t
 he proof requires new techniques.  The proof uses work of Ricks on recogni
 sing product splittings from the Tits boundary as well as work of Guralnik
  and Swenson on general dynamics of a CAT(0) group on both the visual and 
 Tits boundary. \n\nThis is (recent) joint work with Jankiewicz\, Karrer\, 
 and Sathaye.\n
LOCATION:https://researchseminars.org/talk/GaTO/50/
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