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SUMMARY:Laurent Bartholdi (Goettingen)
DTSTART:20201015T150000Z
DTEND:20201015T160000Z
DTSTAMP:20260423T004637Z
UID:OSUGGT/10
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/OSUGGT/10/">
 Domino problems on graphs and groups</a>\nby Laurent Bartholdi (Goettingen
 ) as part of Ohio State Topology and Geometric Group Theory Seminar\n\n\nA
 bstract\nFor a fixed edge-labelled graph\, the "domino problem" asks: "giv
 en a collection of labelled dominoes (with numbers on their ends)\, can on
 e put a domino on each edge of the graph in such a manner that edge labels
  and vertex numbers match?''\n\nIn spite of its naive appearence\, this pr
 oblem is deeply connected to (monadic\, second-order) logic\; remarkably\,
  it is undecidable for graphs such as the infinite square grid – the "Wa
 ng tiling problem".\n\nI will consider it on graphs produced from a group 
 action: Cayley graphs\, Schreier graphs. I will exhibit a class of graphs 
 for which the problem is decidable\, as well as interesting examples not c
 ontaining grids yet also having undecidable domino problem.\n\nPart of thi
 s is joint work with Ville Salo.\n
LOCATION:https://researchseminars.org/talk/OSUGGT/10/
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