Shafarevich–Tate Groups of Holomorphic Lagrangian Fibrations

Mon Oct 7, 2024 4:30 p.m.—5:30 p.m.
Exterior of Sheffield-Sterling-Strathcona Hall featuring a stone carving of Yale's coat of arms and motto

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Seminar: 
Geometry, Symmetry and Physics

Event time: 
Monday, October 7, 2024 - 4:30pm

Location: 
KT 801

Speaker: 
Anna Abasheva

Speaker affiliation: 
Columbia University

Event description: 
Consider a holomorphic fibration P : X → B whose general fiber is a torus. Its Shafarevich–Tate group parametrizes fibrations that are isomorphic to P locally over the base, i.e., fibers are the same but are glued in a different way. The fibrations with this property are called Shafarevich–Tate twists. I’ll describe the Shafarevich–Tate group in the case when P is a Lagrangian fibration on a compact hyperkähler manifold X. Then we’ll figure out which twists are projective, which are Kähler, and which are non-Kähler. In particular, I’ll show how to obtain the Bogomolov–Guan manifold, which is the only known example of a non-Kähler holomorphic symplectic manifold, as a Shafarevich-Tate twist of a Kähler manifold.