Universiteit Leiden

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Workshop on Algorithms in Number Theory and Arithmetic Geometry

31 July 2017 - 4 August 2017
Snellius Building
Niels Bohrweg 1
2333 CA Leiden
Lorentz Center (second floor of the Snellius building)


The theme of the workshop will be explicit and computational methods in number theory and arithmetic geometry in a broad sense. The format will include scientific talks as well as time for informal collaboration and for coding projects related to (for example) PARI/GP, SageMath or the L-Functions and Modular Forms Database.


  • Martin Bright (Universiteit Leiden)
  • Nils Bruin (Simon Fraser University)
  • Peter Bruin (Universiteit Leiden)
  • Henri Cohen (Université de Bordeaux)
  • Vincent Delecroix (LABRI, Bordeaux)
  • Lassina Dembélé (Max-Planck-Institut für Mathematik, Bonn)
  • Maarten Derickx (Universität Bayreuth)
  • Bas Edixhoven (Universiteit Leiden)
  • Dino Festi (Johannes-Gutenberg-Universität Mainz)
  • Tom Fisher (University of Cambridge)
  • Jean-Pierre Flori (ANSSI, Paris)
  • Stevan Gajovic (Universität Oldenburg)
  • Richard Griffon (Universiteit Leiden)
  • Florian Heß (Universität Oldenburg)
  • David Holmes (Universiteit Leiden)
  • Jinbi Jin (MPIM, Bonn)
  • Matthias Junge (Universität Oldenburg)
  • Kamal Khuri-Makdisi (American University of Beirut)
  • Pınar Kılıçer (Universität Oldenburg)
  • Michiel Kosters (University of California, Irvine)
  • Joey van Langen (VU Amsterdam)
  • Chloe Martindale (Technische Universiteit Eindhoven)
  • Marc Masdeu (Universitat Autònoma de Barcelona)
  • Marco Melles (Universität Oldenburg)
  • Hartmut Monien (Universität Bonn)
  • Jan Steffen Müller (Universität Oldenburg)
  • Filip Najman (University of Zagreb)
  • Bartosz Naskręcki (University of Bristol/Adam Mickiewicz University)
  • Christian Neurohr (Universität Oldenburg)
  • Aurel Page (University of Warwick)
  • Pavel Solomatin (Universiteit Leiden/Université de Bordeaux)
  • Anna Somoza (Universitat Politècnica de Catalunya/Universiteit Leiden)
  • Marco Streng (Universiteit Leiden)
  • Jeroen Sijsling (Universität Ulm)
  • Amadou Tall (Université Cheikh-Anta-Diop, Dakar)
  • Jan Tuitman (KU Leuven)
  • Christian Wuthrich (University of Nottingham)


Monday 31 July    
9:00–9:25 Arrival, coffee/tea  
9:25 Introduction  
9:30–10:30 Vincent Delecroix Volumes, intersection and combinatorics in $\overline{\mathcal{M}_{g,n}}$
11:00 Planning/introduction of projects  
13:00–16:00 Discussion/coding  
16:00–17:00 Tom Fisher Some algebras associated to genus one curves
17:00 Status reports  
Tuesday 1 August    
9:30–10:30 Jeroen Sijsling Computing endomorphisms of Jacobians
11:00–12:00 Jean-Pierre Flori Computing embeddings of finite fields
13:00 Marc Masdeu One approach to packaging Sage code
followed by Hartmut Monien Computing Belyi maps for sporadic groups
         –16:00 Discussion/coding  
16:00–17:00 Nils Bruin A tool for numerically computing period matrices of algebraic Riemann surfaces
17:00 Status reports  
Wednesday 2 August    
9:30–10:30 Lassina Dembélé On the compatibility between base change and Hecke action
11:00–12:00 Henri Cohen Classical Modular Forms in Pari/GP
12:10–13:10 Maarten Derickx A-gonalities of curves and the existence of infinitely many points of degree d
  Free afternoon  
Thursday 3 August    
9:30–10:30 Kamal Khuri-Makdisi Jacobian group operations for typical divisors on curves
11:00–12:00 Pavel Solomatin On Artin L-functions and Gassmann Equivalence for Global Function Fields
13:00–16:00 Discussion/coding  
16:00–17:00 Bartosz Naskręcki Hypergeometric motives of low degrees
17:00 Status reports  
19:00– Dinner at Pakhuis  
Friday 4 August    
9:30–10:30 Jan Tuitman Computing zeta functions of smooth projective hypersurfaces
11:00–12:00 Filip Najman Hyperelliptic modular curves X0(n) and isogenies of elliptic curves over quadratic fields
12:10–13:10 Christian Wuthrich Numerical modular symbols
14:00– Discussion/coding  


Abstracts of the talks (PDF)

CoCalc project for discussion/coding sessions

Wiki page for SageMath-related projects


Unfortunately, it is no longer possible to register for this workshop.

For more information, please send an e-mail to Peter Bruin <P.J.Bruin@math.leidenuniv.nl>.


Participants whose accommodation is booked by us will stay at the Hilton Garden Inn, Oegstgeest (very close to the institute).

Here is a non-exhaustive list of further hotel suggestions.

Close to the institute:

  • Holiday Inn
  • Van der Valk Hotel Leiden

In the city centre:

  • De Doelen
  • Nieuw Minerva

Close to the train station:

  • Golden Tulip
  • Ibis


Organiser: Peter Bruin.

Financially supported by NWO (Netherlands Organisation for Scientific Research).