Organizers: Arne Smeets and Ben Moonen (Nijmegen), Johannes Nicaise (Imperial College/Leuven), Lenny Taelman (Amsterdam), Nero Budur (Leuven) and Bas Edixhoven (Leiden)

Next meeting: March 23, 2018 at Leiden University, jointly with the Séminaire Grothendieck

The next Belgian-Dutch Algebraic Geometry seminar will be combined with the Grothendieck Seminar. This will take place on Friday, March 23, 2018 in Leiden. The speakers are José Burgos, Florian Ivorra and Peter Jossen.

This meeting is sponsored by the Diamant Cluster

Venue: Leiden University, Havingazaal, LMUY building. Use the entrance of the Oort building (Niels Bohrweg 2, 2333 CA Leiden), take the stairs to the walkway on the first floor to the LMUY building, at the end turn left and then immediately right, the room is at the end on your right. Coordinates of the lecture room: 52.168315, 4.460591.

A dinner will be organised, starting at 18:30. If you want to participate in this dinner then sign up for it by sending an email to Bas Edixhoven,, and include your dietary wishes if necessary, no later than Wednesday March 14.

Programme (click a title to show/hide the abstract)

13:30-14:30 Florian Ivorra (FRIAS, Freiburg) Quasi-unipotent motives
Abstract: Quasi-unipotent motives were introduced by J. Ayoub who related them to motives of rigid analytic varieties. In this talk, I will give an overview of their properties focusing on their relations with nearby cycles functors and monodromy action.
15:00-16:00 Peter Jossen (ETH Zürich) Galois groups and Motivic Fundamental groups
Abstract: Let k a subfield of the complex numbers. I will explain what is known and what is still conjectured about the relation between the absolute Galois group of k and various motivic fundamental groups of k. The motivic fundamental groups are: the one obtained from Nori's tannakian category of mixed motives, the one obtained from Ayoub's weak tannakian formalism, and André's fundamental group for motives with respect to motivated cycles.
16:30-17:30 José Burgos Gil (ICMAT, Madrid) Grothendieck's period conjecture and zeta values
Abstract: In this survey talk we will give an overview of Grothendieck's period conjecture and explain how this conjecture implies that the values of the Riemann zeta function at odd integers bigger that 3 are algebraically independent.

Previous meetings of the seminar (in reverse chronological order)

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) p-adic 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 blow-ups 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 bi-arrangements
Misha Verbitsky (ULB, Bruxelles) Transcendental Hodge algebra

June 11 and 12, 2015 in Nijmegen, joint with NoGAGS

Daniel Greb (Duisburg-Essen) Movable curves and semistable sheaves
Klaus Künnemann (Regensburg) A tropical approach to non-archimedean Arakelov geometry
Kevin Buzzard (Imperial College) Pre-adic 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 D-modules in positive characteristic
Christian Lehn (Hannover) Rational curves on singular cubic fourfolds
Ulf Kühn (Hamburg) A geometric approach to constructing elements of K2 of curves

November 14, 2014 at the University of Amsterdam

Minhyong Kim (Oxford) Non-abelian reciprocity laws and Diophantine geometry
Mingmin Shen (UvA) Multiplicative Chow-Künneth 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
Frank-Olaf 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
Jean-Benoît 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 S-arithmetic groups
Matthieu Romagny (Jussieu) Models of groups schemes of roots of unity
Mircea Mustaţă (Michigan) Adjoint line bundles in positive characteristic