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SUMMARY:Marcin Wrochna (University of Oxford)
DTSTART:20201028T103000Z
DTEND:20201028T113000Z
DTSTAMP:20260423T021422Z
UID:CATGT/14
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/CATGT/14/">U
 nderstanding homomorphism approximation problems using topology</a>\nby Ma
 rcin Wrochna (University of Oxford) as part of Applications of Combinatori
 cs in Algebra\, Topology and Graph Theory\n\n\nAbstract\nWe consider an ap
 proximation version of the graph colouring computational problem: can we e
 fficiently distinguish a 3-colourable graph from a graph that is not even 
 100-colourable? More generally\, given a structure that is promised to hav
 e a homomorphism to G\, can we at least find a (much weaker) homomorphism 
 to H? This is an ages-old question in which we recently made some surprisi
 ng progress using topology and algebra\, e.g. studying maps from a torus t
 o a sphere\, or looking at some adjoint functors in the category of graphs
 . I will introduce all necessary basics to explain these unexpected connec
 tions. Joint work with Andrei Krokhin\, Jakub Opršal\, and Standa Živný
 .\n
LOCATION:https://researchseminars.org/talk/CATGT/14/
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