## 2016

### Intercity Number Theory Seminar

22 January, Groningen. Bernoulliborg, room 105- 12:00–13:00
- Teresa Crespo Barcelona, Hopf Galois separable extensions
In December 2020, Peter Scholze posed a challenge to formally verify the main theorem on liquid ℝ-vector spaces, which is part of his joint work with Dustin Clausen on condensed mathematics. I took up this challenge with a team of mathematicians to verify the theorem in the Lean proof assistant. Half a year later, we reached a major milestone, and our expectation is that shortly we will have completed the full challenge. In this talk I will give a brief motivation for condensed/liquid mathematics, a demonstration of the Lean proof assistant, and discuss our experiences formalizing state-of-the-art research in mathematics.
- 13:30–14:30
- Ane Anema Groningen, Faltings method, Galois extensions of exponent four and abelian surfaces over Q
In December 2020, Peter Scholze posed a challenge to formally verify the main theorem on liquid ℝ-vector spaces, which is part of his joint work with Dustin Clausen on condensed mathematics. I took up this challenge with a team of mathematicians to verify the theorem in the Lean proof assistant. Half a year later, we reached a major milestone, and our expectation is that shortly we will have completed the full challenge. In this talk I will give a brief motivation for condensed/liquid mathematics, a demonstration of the Lean proof assistant, and discuss our experiences formalizing state-of-the-art research in mathematics.
- 14:45–15:45
- Max Kronberg Groningen, Construction of Torsion Points on Jacobians of Curves using Hensel's Lemma
In December 2020, Peter Scholze posed a challenge to formally verify the main theorem on liquid ℝ-vector spaces, which is part of his joint work with Dustin Clausen on condensed mathematics. I took up this challenge with a team of mathematicians to verify the theorem in the Lean proof assistant. Half a year later, we reached a major milestone, and our expectation is that shortly we will have completed the full challenge. In this talk I will give a brief motivation for condensed/liquid mathematics, a demonstration of the Lean proof assistant, and discuss our experiences formalizing state-of-the-art research in mathematics.
- 16:00–17:00
- Zbigniew Hajto Kraków, Polynomial automorphisms and Picard-Vessiot theory

### Intercity Number Theory Seminar

5 February, Leiden. Snellius building, room 312- 11:15–12:15
- Martin Bright Leiden, Failures of weak approximation in families
- 13:15–14:15
- Daniel Loughran Hannover, Fibrations with few rational points
- 14:30–15:30
- Elisa Leiden, Twists of the Klein quartic: classification and modular interpretation
- 15:45–16:45
- Rodolphe Richard Leiden, Witt vectors and p-adic differential equations

### Intercity Number Theory Seminar

4 March, UvA Amsterdam. The first three talks are in room F3.20 of the KdVI (entrance Nikhef), Science Park 107.Lenny Taelman's inaugural lecture will take place in the Oude Lutherse kerk (Singel 411, corner with Spui)

- 10:30–11:30
- Ronald van Luijk Leiden, Concurrent lines on del Pezzo surfaces of degree one
- 11:45–12:45
- Christophe Debry KU Leuven and UvA, Special values in positive characteristic
- 13:45–14:45
- Ben Moonen Nijmegen, Can every K3 be dominated by a product of curves?
- 16:00–17:00
- Lenny Taelman UvA, Onmogelijke verbanden

### Intercity Number Theory / Beeger Seminar

24 March, Leiden. This is a Thursday! Snellius building, room 312.- 11:00–12:00
- Rob Tijdeman Leiden, Finding well approximating lattices for a finite set of points.
- 13:15–14:15
- Florian Luca Johannesburg, Diversity in parametric families of number fields
- 14:45–15:45
- Jan-Hendrik Evertse Leiden, Results and open problems related to Schmidt's Subspace Theorem
- 16:00–17:00
- James Maynard Oxford, Polynomials representing primes

### The Big Picture, workshop on the occasion of Jan Stienstra's retirement

8 April, Utrecht. Unfortunately, the workshop will be moved to a later date, to be specified.See the website.

### 10th Belgian-Dutch Algebraic Geometry Day

22 April, Leuven. Kasteel van Arenberg, KU Leuven wetenschapscampus, Heverlee (there will be signs and there is parking next to the castle)- 13:45–14:45
- Sho Tanimoto Copenhagen, Towards a refinement of Manin's conjecture
- 15:00–16:00
- John Christian Ottem Oslo, Effective cones of cycles on blow-ups of projective space.
- 16:30–17:30
- Bruno Chiarellotto Padova, Monodromy action and special fiber for semistable schemes over a DVR

### Intercity Number Theory Seminar

19 May, Eindhoven. PhD defense Emil Horobet. Thursday! The talks will be in MF 15; the defense in Aud 4.- 12:00–12:45
- Bernd Sturmfels UC Berkeley, Nearest Points on Toric Varieties
- 13:30–14:15
- Bernard Mourrain Inria, Sparse decomposition from moments.
- 14:30–15:15
- Monique Laurent CWI and Tilburg University, Completely positive semidefinite matrices: some properties and applications
- 16:00–17:00
- Emil Horobet TU Eindhoven, PhD defense

### Intercity Number Theory Seminar

10 June, Leuven. Departement wiskunde, lokaal 01.07, Celestijnenlaan 200B, 3001 Heverlee, België- 13:00–13:45
- Jennifer Balakrishnan Oxford, Coleman integration for hyperelliptic curves
- 14:00–14:45
- Jan Tuitman Leuven, Coleman integration for general curves
- 15:15–16:15
- Giulia Battiston Heidelberg, A theory of Galois descent for finite inseparable extensions
- 16:30–17:30
- Margaret Bilu ENS Paris, Motivic Euler products

### “Hecke meets Galois” - a minisymposium

13 June, Utrecht. PhD defense Valentijn Karemaker, academiegebouw- 09:30–10:15
- Maarten Solleveld Radboud U., Instances of the local Langlands correspondence, based on class field theory
- 10:20–11:05
- Elena Mantovan Caltech, Differential operators and families of automorphic forms on unitary groups of arbitrary signature
- 11:30–12:15
- Jeroen Sijsling U. Ulm, Reconstructing plane quartics from their invariants
- 14:30–15:30
- Valentijn Karemaker U. Utrecht, PhD defense: Hecke algebras, Galois representations, and abelian varieties

### Intercity Number Theory Seminar

26 August, Leiden. Havinga zaal, Gorlaeus building. (Enter through the main entrance of the Gorlaeus building. Walk up the stairs, cross the long corridor and pass through the doors at the end of the corridor. Directly after passing those doors, turn to the right and you will find the Havingazaal 50 meters down the hall on the right hand side.)This is the last day of the workshop Mathematical Structures for Cryptography.

- 09:45–10:45
- Nadia Heninger University of Pennsylvania, Cryptographic applications of capacity theory
- 11:15–12:15
- Florian Hess Carl von Ossietzky Universität Oldenburg, Asymptotically fast arithmetic in Jacobians of curves of large genus
- 13:20–13:50
- Andreas Enge INRIA Bordeaux-Sud-Ouest, Short addition sequences for theta functions
- 14:00–15:00
- Chaoping Xing Nanyang Technological University, Singapore, Codex and applications to local decoding of Reed-Muller codes

### PhD defense Maarten Derickx

21 September, Leiden. room C102 Sterrewacht, Sterrenwachtlaan 11, 2311 GP, Leiden- 11:15–12:15
- Maarten Derickx Leiden, PhD defence (Academiegebouw, Rapenburg 73)
- 14:00–15:00
- Pierre Parent Université de Bordeaux, Rational points of modular curves: an arakelovian point of view
- 15:15–16:15
- Marusia Rebolledo Université Blaise Pascal Clermont-Ferrand 2, Survey of Yuan-Zhang proof of averaged Colmez conjecture.
- 16:30–17:30
- Maarten Derickx Universiteit Leiden, Torsion points on elliptic curves over number fields of degree > 6

### Intercity Number Theory Seminar

7 October, Leiden. Snellius Building, room B03- 11:15–12:15
- Gabriel Zalamansky Universiteit Leiden, The complexity of a flat Groupoid
- 13:30–14:30
- Jinbi Jin Universiteit Leiden - MPIM Bonn, Computability of the étale Euler-Poincaré characteristic with finite coefficients
- 14:45–15:45
- Erik Visse Univeriteit Leiden, Explicit bounds for the transcendental Brauer group of Kummer surfaces over a number field
- 16:00–17:00
- Richard Griffon Universiteit Leiden, Analogue of the Brauer-Siegel for the Legendre elliptic curves over function fields

### Intercity Number Theory Seminar

11 November, UvA and VU Amsterdam. At the VU: before lunch in room WN-F619 and after lunch in room WN-M639 (both in the W&N building).- 11:00–12:00
- Martin Orr Imperial College London, Finiteness theorem for K3 surfaces with complex multiplication
- 13:15–14:15
- James Lewis University of Alberta, A Going-up Theorem in K-Theory and a Question of Bruno Kahn
- 14:30–15:30
- Chun Yin Hui VU Amsterdam, Invariant dimensions, semisimplicity, and maximality of geometric monodromy action
- 16:00–17:00
- Wadim Zudilin University of Newcastle and RU Nijmegen, Short random walks and Mahler measures