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SUMMARY:Daniel Corey (University of Wisconsin-Madison)
DTSTART:20210312T153000Z
DTEND:20210312T163000Z
DTSTAMP:20260422T172221Z
UID:TGiZ/21
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/TGiZ/21/">Th
 e Ceresa class: tropical\, topological\, and algebraic</a>\nby Daniel Core
 y (University of Wisconsin-Madison) as part of Tropical Geometry in Frankf
 urt/Zoom TGiF/Z\n\n\nAbstract\nThe Ceresa cycle is an algebraic cycle atta
 ched to a smooth algebraic curve. It is homologically trivial but not alge
 braically equivalent to zero for a very general curve. In this sense\, it 
 is one of the simplest algebraic cycles that goes ``beyond homology.'' The
  image of the Ceresa cycle under a certain cycle class map produces a clas
 s in étale homology called the Ceresa class. We define the Ceresa class f
 or a tropical curve and for a product of commuting Dehn twists on a topolo
 gical surface. We relate these to the Ceresa class of a smooth algebraic c
 urve over C((t)). Our main result is that the Ceresa class in each of thes
 e settings is torsion. Nevertheless\, this class is readily computable\, f
 requently nonzero\, and implies nontriviality of the Ceresa cycle when non
 zero. This is joint work with Jordan Ellenberg and Wanlin Li.\n
LOCATION:https://researchseminars.org/talk/TGiZ/21/
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