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X-WR-CALNAME:[gt.go] - 'Triangle-free graphs and the odd Hadwiger conjectur
 e' by Yuval Wigderson
X-WR-TIMEZONE:Europe/Paris
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TZID:Europe/Paris
TZUNTIL:20271031T010000Z
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DTSTART:20251026T030000
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TZOFFSETTO:+0100
RDATE:20261025T030000
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DTSTART:20250330T020000
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RDATE:20260329T020000
RDATE:20270328T020000
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DTSTAMP:20260412T174833Z
CLASS:PUBLIC
DESCRIPTION:Hadwiger's conjecture\, first formulated in 1943\, is a vast ge
 neralization of the four-color theorem\, and remains one of the central op
 en problems in graph theory. An even stronger statement\, known as the odd
  Hadwiger conjecture\, was proposed in 1993 by Gerards and Seymour. For ma
 ny decades\, progress on one problem was quickly followed by progress on t
 he other\, and recent developments indicate that Hadwiger's conjecture and
  its odd variant are very closely linked. \n\nHowever\, as it turns out\, 
 the odd Hadwiger conjecture is false. The key ingredient to the counterexa
 mples is a new random model of triangle-free graphs\, which arose in the r
 ecent breakthrough work of Hefty et al. on off-diagonal Ramsey numbers. In
  this talk\, I will describe this construction\, and sketch how it can be 
 used to disprove the odd Hadwiger conjecture. \n\nBased on joint work with
  Marcus Kühn\, Lisa Sauermann\, and Raphael Steiner. \n\n(Yuval Wigderson)
  [ETH - Institute for Theoretical Studies] \n\n\nVérifiez que vous êtes bi
 en inscrits sur le site du [gdr-ifm-gt-graphes] : [ https://gtgraphes.labr
 i.fr/pmwiki/pmwiki.php/Equipes/Equipes#membres | https://gtgraphes.labri.f
 r/pmwiki/pmwiki.php/Equipes/Equipes#membres ] \n\nRemarks / Remarques \n\n
 Find all the information of the working group on this [ https://grapheseto
 ptimisation.labri.fr/pmwiki.php/Groupe/GT?userlang=en | web page ] . \nRet
 rouvez toutes les informations du GT sur cette [ https://graphesetoptimisa
 tion.labri.fr/pmwiki.php/Groupe/GT | page web ] . \n\n\n\nImport automatiq
 ue depuis https://webmel.u-bordeaux.fr/home/bf-labri.ca@u-bordeaux.fr/gt.g
 o.ics par sync_icals_to_drupal.py pour GT-GO
DTSTART;TZID=Europe/Paris:20260320T140000
DTEND;TZID=Europe/Paris:20260320T143000
LOCATION:LaBRI/178
SEQUENCE:0
SUMMARY:[gt.go] - 'Triangle-free graphs and the odd Hadwiger conjecture' by
  Yuval Wigderson
TRANSP:OPAQUE
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