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BEGIN:VEVENT
SUMMARY:Dessins d'enfants and the Grothendieck-Teichmüller group
DTSTART:20151201T151500
DTEND:20151201T170000
DTSTAMP:20260917T083809Z
UID:4dfc26b612797b80eefbd9875b7b3aa1791c41ee095f60252feef91f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Pierre Guillot\, (Strasbourg)\nDuring the first part of the ta
 lk I will describe the\ntheory of dessins d'enfants\, which states the equ
 ivalence of a number\nof seemingly quite different categories\, such as gr
 aphs embedded on\nsurfaces\, étale algebras over a field of rational frac
 tions (with\nvarious coefficients)\, or finite sets endowed with two disti
 nguished\npermutations. It follows that the absolute Galois group of QQ ac
 ts on\nall these categories\, and one can show that the action is faithful
 .\nAs a result\, this Galois group injects into the\nGrothendieck-Teichmü
 ller group\, of which I will give an elementary\ndescription. In the secon
 d part of the talk\, I shall explain how to\nmake concrete calculations\, 
 and propose a few open questions.
LOCATION:CHB331 http://plan.epfl.ch/?zoom=20&recenter_y=5864117.69298&rece
 nter_x=731381.1146&layerNodes=fonds\,batiments\,labels\,information\,parki
 ngs_publics\,arrets_metro\,transports_publics&floor=3&q=CHB331
STATUS:CONFIRMED
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