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SUMMARY:Marcelo Atallah (University of Sheffield)
DTSTART:20251007T140000Z
DTEND:20251007T150000Z
DTSTAMP:20260423T005658Z
UID:Geolis/173
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/Geolis/173/"
 >C⁰-rigidity of the Hamiltonian diffeomorphism group of symplectic ratio
 nal surfaces</a>\nby Marcelo Atallah (University of Sheffield) as part of 
 Geometria em Lisboa (IST)\n\n\nAbstract\nA natural question bridging the c
 elebrated Gromov–Eliashberg theorem and the C⁰-flux conjecture is whet
 her the identity component of the group of symplectic diffeomorphisms is C
 ⁰-closed in Symp(M\,ω). Beyond surfaces and the cases in which the Tore
 lli subgroup of Symp(M\,ω) coincides with the identity component\, little
  is known. In joint work with Cheuk Yu Mak and Wewei Wu\, we show that\, f
 or all but a few positive rational surfaces\, the group of Hamiltonian dif
 feomorphisms is the C⁰-connected component of the identity in Symp(M\,ω
 )\, thereby giving a positive answer in this setting. Here\, “positive r
 ational surface” essentially means a k-point blow-up of CP² whose sympl
 ectic form evaluates positively on the first Chern class.\n
LOCATION:https://researchseminars.org/talk/Geolis/173/
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