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SUMMARY:Weiwei Wu (Zhejiang University)
DTSTART:20230321T130000Z
DTEND:20230321T140000Z
DTSTAMP:20260423T022744Z
UID:Geolis/115
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/Geolis/115/"
 >Symplectic Torelli groups for positive rational surfaces</a>\nby Weiwei W
 u (Zhejiang University) as part of Geometria em Lisboa (IST)\n\n\nAbstract
 \nDonaldson (folklore) asked whether Lagrangian Dehn twists always generat
 e the symplectic mapping class groups in real dimension four. So far\, all
  known examples indicate this is true\, even though the symplectic Torelli
  group is generally much larger than the algebraic one. Yet there are only
  very few cases people could prove this as a theorem.\n\nWe will define a 
 notion of "positive rational surfaces"\, which is equivalent to the ambien
 t symplectic manifolds of (symplectic) log Calabi-Yau pairs. We compute th
 e symplectic Torelli group for the positive rational surfaces and confirm 
 Donaldson's conjecture as a result. We also answer several other questions
  about the symplectic Torelli groups in dimension $4$.\n
LOCATION:https://researchseminars.org/talk/Geolis/115/
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