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DTSTART:20250309T070000
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UID:69ce959a3ab4d
DTSTART;TZID=America/Toronto:20260223T144500
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260223T154500
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/graphs-and-m
 atroids-agnes-totschnig-colouring-graphs
SUMMARY:Graphs and Matroids - Agnes Totschnig-Colouring graphs with forbidd
 en\n7-vertex minors
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Agnes Totschnig\n\nAFFILIATION:\n McGill University\
 n\nROOM:\n MC 5479\n\nABSTRACT:In 1943\, Hadwiger conjectured that every k
 -chromatic graph\nhas a K_k-minor. While the cases k = 5 and k = 6 have be
 en shown to be\nequivalent to the Four Colour Theorem\, respectively by Wa
 gner\, and in\nseminal work by Robertson\, Seymour and Thomas\, the cases 
 k at least 7\nremain open. We show that any 7-chromatic graph has as a min
 or the\ncomplete graph K_7 with two adjacent edges removed\, by extending 
 work\nof Kawarabayashi and Toft and by proving a new edge-extremal bound.\
 nThis improves Jakobsen’s result with two arbitrary edges removed.\nJoin
 t work with Sergey Norin.
DTSTAMP:20260402T161314Z
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