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SUMMARY:Marco Mazzuchelli (École normale supérieure de Lyon)
DTSTART:20210406T160000Z
DTEND:20210406T170000Z
DTSTAMP:20260423T022627Z
UID:Geolis/39
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/Geolis/39/">
 What does a Besse contact sphere look like?</a>\nby Marco Mazzuchelli (Éc
 ole normale supérieure de Lyon) as part of Geometria em Lisboa (IST)\n\n\
 nAbstract\nA closed connected contact manifold is called Besse when all of
  its Reeb orbits are closed (the terminology comes from Arthur Besse's mon
 ograph "Manifolds all of whose geodesics are closed"\, which deals indeed 
 with Besse unit tangent bundles). In recent years\, a few intriguing prope
 rties of Besse contact manifolds have been established: in particular\, th
 eir spectral and systolic characterizations. In this talk\, I will focus o
 n Besse contact spheres. In dimension 3\, it turns out that such spheres a
 re strictly contactomorphic to rational ellipsoids. In higher dimensions\,
  an analogous result is unknown and seems out of reach. Nevertheless\, I w
 ill show that at least those contact spheres that are convex still "resemb
 le" a contact ellipsoid: any stratum of the stratification defined by thei
 r Reeb flow is an integral homology sphere\, and the sequence of their Eke
 land-Hofer capacities coincides with the full sequence of action values\, 
 each one repeated according to a suitable multiplicity. This is joint work
  with Marco Radeschi.\n
LOCATION:https://researchseminars.org/talk/Geolis/39/
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