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UID:20250812T113426EDT-8068ulEMJU@132.216.98.100
DTSTAMP:20250812T153426Z
DESCRIPTION:Title: Semistability of G-torsors and integration questions in 
 characteristic p>0\n\nAbstract: Constructing quotients is a natural but di
 fficult question in algebraic geometry. A key tool for this purpose is the
  notion of semistability. Let k be a field and X be a k-curve. Let also G 
 be a reductive group over X obtained from a reductive group over k by base
  change. Semistability for G-torsors can be defined by several ways. In th
 is talk we present Atiyah--Bott and Behrend's approaches. We then explain 
 why the first approach can be extended to some positive characteristics an
 d why both of these approaches lead to the same notion (when they are both
  well-defined). For this\, I established during my PhD an analogue in posi
 tive characteristic of a theorem of Morozov\, which classifies\, in charac
 teristic 0\, parabolic subalgebras of a reductive group by means of their 
 nilradical.\n	\n	In the second part of the talk\, I will present this analog
 ue and detail some of the positive characteristic issues its proof raised.
  More specifically\, I will focus on integration questions for nil algebra
 s in this context: roughly speaking I will discuss the existence of a map 
 that plays the role of the exponential map (defined by its power series)\,
  even in small characteristics.\n\n \n\nQuébec-Vermont Number Theory Semin
 ar\n	Web - For details\, please contact: martinez [at] crm.umontreal.ca\n\n
  \n
DTSTART:20220127T180000Z
DTEND:20220127T193000Z
SUMMARY:Marion Jeannin\, Université Lyon 1
URL:/mathstat/channels/event/marion-jeannin-universite
 -lyon-1-336448
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