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BIMSA-YMSC Tsinghua Number Theory Seminar
Explicit realization of elements of the Tate-Shafarevich group constructed from Kolyvagin classes
Explicit realization of elements of the Tate-Shafarevich group constructed from Kolyvagin classes
Organizers
Yueke Hu
, Emmanuel Lecouturier
,
Cezar Lupu
Speaker
Lazar Radicevic
Time
Wednesday, December 15, 2021 4:00 PM - 5:00 PM
Venue
1118
Online
Zoom 388 528 9728
(BIMSA)
Abstract
We consider the Kolyvagin cohomology classes associated to an elliptic curve E defined over ℚ from a computational point of view. We explain how to go from a model of a class as an element of (E(L)/pE(L))^Gal(L/ℚ), where p is prime and L is a dihedral extension of ℚ of degree 2p, to a geometric model as a genus one curve embedded in ℙ^(p−1). We adapt the existing methods to compute Heegner points to our situation, and explicitly compute them as elements of E(L). Finally, we compute explicit equations for several genus one curves that represent non-trivial elements of the p-torsion part of the Tate-Shafarevich group of E, for p≤11, and hence are counterexamples to the Hasse principle.