On June 21, 2019, the next meeting of the BelgianDutch Algebraic Geometry seminar will be held at the University of Amsterdam. Location: room G2.10 at Science Park 904, Amsterdam.
Programme (click a title to show/hide the abstract) 

13:0014:00  Diletta Martinelli (Edinburgh)  On the geometry of contractions of the Moduli Space of sheaves of a K3 surface
Abstract: I will describe how recent advances have made possible to study the birational geometry of hyperkaehler varieties of K3type using the machinery of wallcrossing and stability conditions on derived categories as developed by Tom Bridgeland. In particular Bayer and Macrì relate birational transformations of the moduli space M of sheaves of a K3 surface X to wallcrossing in the space of Bridgeland stability conditions Stab(X). I will explain how it is possible to refine their analysis to give a precise description of the geometry of the exceptional locus of any birational contraction of M.

14:3015:30  Zsolt Patakfalvi (EPFL)  On the BeauvilleBogomolov decomposition in positive characteristic
Abstract: I will present a work in progress joint with Maciej Zdanowicz aiming to prove a positive characteristic version of the BeauvilleBogomolov decomposition. Over the complex numbers this decomposition was shown using differential geometry methods in the 70's and the 80's. It concerns varieties with trivial canonical bundle, which we call Ktrivial here. The main statement over the complex number is that smooth projective Ktrivial varieties admit an étale cover which splits as a product of three types of varieties: abelian, CalabiYau and symplectic. I will present a similar statement in positive characteristic for (weakly) ordinary Ktrivial varieties, the proof of which uses purely positive characteristic methods.

16:0017:00  Yichao Tian (Strasbourg)  Geometry of unitary Shimura varieties at nonquasisplit primes and arithmetic applications
Abstract: Let E/Q be an imaginary quadratic number field, and G be the unitary group associated to a Hermitian space over E of dimension n of signature type (1,n1). We consider a prime number p inert in E such that the Hermitian space is not quasisplit at p. In this talk, I will explain the geometry in characteristic p of the Shimura variety attached to G of maximal level at p. It turns out that the Shimura variety has semistable reduction and one has a very explicit description of its supersingular locus. The intersection of the irreducible components of the supersingular locus encodes interesting arithmetic information. This is part of my joint work in progress with Yifeng Liu, Liang Xiao, Wei Zhang and Xinwen Zhu.

February 1, 2019, at Utrecht University 

Dan Petersen (Stockholm University)  Tautological classes with twisted coefficients  
Donatella Iacono (Università di Bari)  DGLie algebras and deformation of pairs  
Georg Oberdieck (University of Bonn)  Quantum cohomology of the Hilbert scheme of pairs  
September 20 and 21, 2018 at Radboud University Nijmegen 

ChingLi Chai (UPenn)  Sustained pdivisible groups and the foliation on moduli spaces of abelian varieties  
Jörg Wildeshaus (Paris 13)  Weights and conservativity  
Kestutis Cesnavicius (CNRS/ParisSud)  Purity for the Brauer group  
Claire Voisin (Collège de France)  Gonality and zerocycles of abelian varieties  
Victoria Hoskins (FU Berlin)  On the motive of the stack of vector bundles on a curve  
Richard Thomas (Imperial College)  Refined VafaWitten invariants for projective surfaces  
Piotr Achinger (IMPAN, Warsaw)  SerreTate theory for CalabiYau varieties  
June 8, 2018 at the KU Leuven 

Arend Bayer (Edinburgh)  Families of Hyperkaehler varieties via families of stability conditions  
Christian Liedtke (Technische Universität München)  A NéronOggShafarevich criterion for K3 Surfaces  
José Burgos Gil (ICMAT, Madrid)  Grothendieck's period conjecture and zeta values  
March 23, 2018 at Leiden University 

Videos of the lectures are available via youtube.  
Florian Ivorra (FRIAS, Freiburg)  Quasiunipotent motives  
Peter Jossen (ETH Zürich)  Galois groups and Motivic Fundamental groups  
Lionel Darondeau (KU Leuven)  Jet differentials and hyperbolicity  
December 15, 2017 at Radboud University Nijmegen 

Johannes Nicaise (Imperial College and Leuven)  Specialization of (stable) rationality in families with mild singularities  
Javier Fresán (École Polytechnique)  Exponential motives  
Michael Groechenig (FU Berlin)  padic integration for the Hitchin system  
December 9, 2016 at the University of Amsterdam 

June Huh (Princeton)  Enumeration of points, lines, planes, etc.  
Dieter Kotschick (München) and Stefan Schreieder (Bonn)  The Hodge ring of Kähler manifolds  
Bhargav Bhatt (Ann Arbor)  Derived splinters in mixed characteristic  
April 22, 2016 at KU Leuven 

Sho Tanimoto (Copenhagen)  Towards a refinement of Manin's conjecture  
John Christian Ottem (Oslo)  Effective cones of cycles on blowups of projective space  
Bruno Chiarellotto (Padova)  Monodromy action and special fiber for semistable schemes over a DVR  
December 11, 2015 at Leiden University 

David Holmes (Leiden)  Models of degenerating jacobians  
Clément Dupont (MPIM Bonn)  Motives of biarrangements  
Misha Verbitsky (ULB, Bruxelles)  Transcendental Hodge algebra  
June 11 and 12, 2015 in Nijmegen, joint with NoGAGS 

Daniel Greb (DuisburgEssen)  Movable curves and semistable sheaves  
Klaus Künnemann (Regensburg)  A tropical approach to nonarchimedean Arakelov geometry  
Kevin Buzzard (Imperial College)  Preadic spaces and adic spaces  
Tim Dokchitser (Bristol)  Local arithmetic of hyperelliptic curves  
David Rydh (KTH Stockholm)  The local structure of Artin stacks  
Lars Kindler (FU Berlin)  Ramification theory for Dmodules in positive characteristic  
Christian Lehn (Hannover)  Rational curves on singular cubic fourfolds  
Ulf Kühn (Hamburg)  A geometric approach to constructing elements of K_{2} of curves  
November 14, 2014 at the University of Amsterdam 

Minhyong Kim (Oxford)  Nonabelian reciprocity laws and Diophantine geometry  
Mingmin Shen (UvA)  Multiplicative ChowKünneth decompositions  
Jakob Stix (Frankfurt)  Gorenstein orders and abelian varieties over finite fields  
May 16, 2014 in Leuven 

Olivier Benoist (Strasbourg)  Complete families of smooth space curves  
FrankOlaf Schreyer (Saarbrücken)  Matrix factorizations and families of curves of genus 15  
Carel Faber (Utrecht)  On the cohomology of the moduli spaces of pointed curves of genus three  
November 22, 2013 in Nijmegen 

Nero Budur (Leuven)  Cohomology jump loci  
Stefan Schröer (Düsseldorf)  Wild quotient surface singularities  
René Schoof (Rome)  Finite group schemes and abelian varieties with good reduction outside one prime  
June 14, 2013 in Leiden 

Walter Gubler (Regensburg)  Normal toric varieties over valuation rings of rank 1  
Gaël Rémond (Bordeaux)  Isogenies and polarizations  
JeanBenoît Bost (Orsay)  Pluripotential theory, heights, and algebraization on arithmetic threefolds  
José Ignacio Burgos Gil (ICMAT Madrid)  The singularities of the invariant metric of the sheaf of Jacobi forms on the universal elliptic curve  
April 19, 2013 in Leuven 

Alejandro Soto (Regensburg)  Toric Varieties over a Valuation Ring  
Sébastien Boucksom (Jussieu)  A uniform version of Izumi's theorem  
Ariyan Javanpeykar (Leiden)  Bounds for Arakelov invariants  algorithmic and Diophantine applications  
December 7, 2012 at the UvA 

Andrei Caldararu (Wisconsin)  Derived intersections  
Eduard Looijenga (Utrecht)  Cohomological dimension of moduli spaces of curves  
Daniel Huybrechts (Bonn)  Cycles on K3 surfaces  
June 15, 2012 in Leuven 

Ted Chinburg (UPenn)  Small generators for Sarithmetic groups  
Matthieu Romagny (Jussieu)  Models of groups schemes of roots of unity  
Mircea Mustaţă (Michigan)  Adjoint line bundles in positive characteristic 