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SUMMARY:Ivan Smith
DTSTART:20210608T140000Z
DTEND:20210608T150000Z
DTSTAMP:20260423T021233Z
UID:Freemath/54
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/Freemath/54/
 ">Lagrangian links on surfaces and the Calabi invariant</a>\nby Ivan Smith
  as part of Free Mathematics Seminar\n\n\nAbstract\nThe identity component
  in the group of area-preserving homeomorphisms of a compact surface admit
 s a `mass-flow’ (or flux) homomorphism to the reals.  We will prove that
  the kernel of this homomorphism is not simple (extending earlier results 
 of Cristofaro-Gardiner\, Humilière and Seyfaddini in the genus zero case)
 \, resolving a question of Fathi from the late 1970s.  The proof appeals t
 o a new family of Lagrangian spectral invariants associated to Lagrangian 
 links on the surface\, which are used to probe the small-scale geometry of
  the surface\; their crucial feature is that they can be used to recover t
 he classical Calabi invariant of a Hamiltonian.  The Floer cohomology theo
 ry behind these spectral invariants is a close cousin of the knot Floer ho
 mology of Ozsváth-Szabó and Rasmussen.  This talk reports on joint work 
 with Dan Cristofaro-Gardiner\, Vincent Humilière\, Cheuk Yu Mak and Sobha
 n Seyfaddini.\n
LOCATION:https://researchseminars.org/talk/Freemath/54/
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