Birational Workshop

Dates: November 20 - 24, 2023
Venue: HIM lecture hall, Poppelsdorfer Allee 45, Bonn
Organizers: Raymond Cheng (Hannover), Mirko Mauri (ISTA), Roberto Svaldi (Milan)



  • Benjamin Bakker
  • Cinzia Casagrande
  • Stéphane Druel
  • Gabi Farkas
  • Lie Fu
  • Osamu Fujino
  • Cécile Gachet
  • Jiao Junpeng
  • Tasuki Kinjo
  • Eduard Looijenga
  • Davesh Maulik
  • Brent Pym
  • Junliang Shen
  • Sho Tanimoto
  • Salim Tayou
  • Michael Temkin
  • Claire Voisin
  • Ziquan Yang



Breakthroughs in algebraic geometry are often achieved after a dramatic change of viewpoint, or by exporting powerful techniques from one field of research to the other, thus providing a new perspective and applications of the original tools. For instance, in the 1980s Mori showed the existence of complex rational curves on Fano varieties via reduction to positive characteristic, the celebrated Bend-and-Break. The theory of foliations was used by Bogomolov and later McQuillan to provide new significant evidence of the Green-Griffiths Conjecture. More recently, Hodge theoretic techniques are reshaping our understanding of hyperkaehler geometry. These are just a few examples among numerous fruitful synergies that have significantly advanced the field.

The workshop will survey several area of algebraic geometry with the goal of fostering interactions between different research groups. The program will focus on the following themes: birational geometry, foliations, hyperkahler geometry, Hodge theory, stacks, and positive characteristic methods.




Monday, November 20

Brent Pym - A local Torelli theorem for log symplectic manifolds

Junliang Shen - A Fourier transform for abelian fibrations

Tuesday, November 21

Sho Tanimoto - Sections of Fano fibrations over curves

Osamu Fujino - Minimal model program for projective morphisms between complex analytic spaces

Michael Temkin - Filling a few holes in the classical resolution of singularities

Cécile Gachet: Orbifold fundamental groups of log Calabi-Yau surface pairs, and the Jordan constant

Wednesday, November 22

Lie Fu - Hochschild cohomology and deformation theory of Hilbert schemes of points on surfaces

Cinzia Casagrande - Fano 4-folds with b2 > 12 are products of surfaces

Ziquan Yang: A new case of BSD conjecture and deformation of line bundles

Thursday, November 23

Tasuki Kinjo - Derived microlocal geometry and virtual invariants

Claire Voisin - On the smoothing problem for cycles in the Whitney range

Friday, November 24

Stéphane Druel - Codimension 1 foliations with projectively flat tangent bundle

Trimester Program guests, who were invited and have confirmed to be at HIM during the period of this workshop, are eligible to attend this event.