## 2013

### Intercity Number Theory Seminar

1 March, Utrecht. A programme around gonalities. Room 611 of the Hans Freudenthal building (the mathematics institute).- 13:00–14:00
- Dion Gijswijt Delft & CWI, Graph gonality a la Baker-Norine: basic concepts, theorems and some open problems
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.
- 14:00–15:00
- Anna Cadoret Ecole Polytechnique, Paris, Gonality, isogonality and points of bounded degree on curves over finitely generated fields in positive characteristic
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.
- 15:30–16:30
- Maarten Derickx Leiden, Gonality of modular curves
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.
- 16:30–17:30
- Janne Kool Utrecht, A combinatorial Li-Yau inequality and rational points on curves

### Intercity Number Theory Seminar

15 March, Leiden. Snellius, room 312. The talks are followed by a reception at the Lorentz center in the Snellius building (adjacent to the math library).- 13:00–14:00
- Pieter Moree MPI Bonn, Sister Beiter and the Novices: Cyclotomic Coefficients and the Young
- 14:30–15:30
- Reinier Bröker Brown, Fourier coefficients of Siegel modular forms
- 16:00–17:00
- Henri Cohen Bordeaux, Enumerating D_\ell number fields of degree \ell and quartic fields with given resolvent

### 3rd Belgian-Dutch Algebraic Geometry day

19 April, Leuven. Room A00.225, Celestijnenlaan 200. See also the map here.- 14:00–15:00
- Alejandro Soto Regensburg, Toric Varieties over a Valuation Ring
- 15:10–16:10
- Sébastien Boucksom Jussieu, A uniform version of Izumi's theorem
- 16:40–17:40
- Ariyan Javanpeykar Leiden, Bounds for Arakelov invariants - algorithmic and Diophantine applications

### Intercity Number Theory Seminar

3 May, Groningen. The lectures are in Room 293 of the Bernoulliborg- 11:45–12:45
- Christina Delfs Oldenburg, Isogenies between Supersingular Elliptic Curves over
*F*_{p} - 13:30–14:30
- Harm Voskuil, Unitary groups and p-adic uniformisation of curves
- 14:45–15:45
- Afzal Soomro Groningen, Special curves of genus four and five over finite fields
- 16:00–17:00
- Jaap Top Groningen, First order nonlinear differential equations

### RISC / Intercity number theory seminar

7 June, CWI Amsterdam. Room L016.- 11:45–12:45
- Ted Chinburg UPenn, Taking on new capacities
- 14:00–14:45
- Juan Garay AT&T Labs, Resource-based Corruption in Secure Computation
- 15:00–15:45
- Iwan Duursma U. Illinois Urbana-Champaign, From abstract curves to efficient secret sharing
- 16:00–16:45
- Chaoping Xing NTU, On torsion limit of algebraic curves over finite fields

### 4th Belgian-Dutch Algebraic Geometry day

14 June, Leiden. Part of the workshop Heights and Moduli Spaces at the Lorentz Center.- 11:10–12:00
- Walter Gubler Regensburg, Normal toric varieties over valuation rings of rank 1
- 13:30–14:20
- Gaël Rémond Bordeaux, Isogenies and polarizations
- 14:20–15:10
- Jean-Benoît Bost Orsay, Pluripotential theory, heights, and algebraization on arithmetic threefolds
- 15:40–16:30
- José Ignacio Burgos Gil ICMAT Madrid, The singularities of the invariant metric of the sheaf of Jacobi forms on the universal elliptic curve

### Intercity Number Theory Seminar

6 September, Leiden. Celebration of Rob Tijdeman's 70th birthday. Room 412 of the Snellius (math department). The lectures are followed by a reception. See also the programme and abstracts.- 11:30–12:30
- Frits Beukers Utrecht, Divisor sums and higher powers
- 13:30–14:30
- Cameron Stewart Waterloo, On a question of Wintner
- 15:00–15:30
- Cor Kraaikamp Delft, Random continued fraction expansions
- 15:30–16:00
- Herman te Riele CWI, A cube whose sum of divisors is again a cube
- 16:00–16:30
- Ionica Smeets Leiden, Toy problems for the retired

### Intercity Number Theory Seminar

11 October, Groningen. Bernoulliborg, room 105.- 12:00–13:00
- Yonatan Harpaz Nijmegen, From linear equations in primes to the fibration method
- 13:45–14:45
- Andreas Stein Oldenburg, Faster sieving methods for solving discrete logarithms in Jacobians of hyperelliptic curves
- 15:00–16:00
- Marius van der Put Groningen, Differential equations of order one (characteristic zero)
- 16:15–17:15
- Jaap Top Groningen, Differential equations of order one (positive characteristic)

### Intercity Number Theory Seminar

25 October, Leiden. The talks are in room B03 of the Snellius building. The PhD Defense of Chao Zhang takes place in the Akademiegebouw in the centre of Leiden (Rapenburg).- 10:00–10:50
- Torsten Wedhorn Paderborn, Newton strata for Shimura varieties of Hodge type
- 11:00–11:50
- Fabrizio Andreatta Milano, A p-adic criterion for good reduction of p-adic curves
- 12:00–12:50
- Bas Edixhoven Leiden, The Andre-Oort conjecture for
*A*_{g}, under GRH, after Pila and Tsimerman - 13:45–14:30
- Chao Zhang Leiden, PhD Defense:
*G*-zips and Ekedahl-Oort Strata for Hodge Type Shimura Varieties

### Intercity Number Theory Seminar

8 November, Eindhoven. Location: LG 1.105.Note that this is

**NOT**in the old Main building,

**NOR**in the new Metaforum building, but

**FURTHER DOWN THE TU/e CAMPUS**. It on the first floor of building number 83 (Laplace Gebouw, LG) on the following map. The entrance is to the East, on the Laplace square. Please keep the additional walking time from the railway station into account when planning your travel.

- 11:30–12:30
- Bernd Sturmfels UC Berkeley / MPI Bonn, Tropicalization of Classical Moduli Spaces
- 13:15–14:15
- Rob Eggermont TU Eindhoven, Noetherianity for infinite-dimensional toric varieties
- 14:20–15:20
- Annette Werner Frankfurt, Faithful tropicalization of the Grassmannian of planes
- 15:45–16:45
- June Huh University of Michigan / MPI Bonn, Geometric Chevalley-Warning conjecture

### 5th Belgian-Dutch Algebraic Geometry day

22 November, Nijmegen. Speakers: Nero Budur, René Schoof, and Stefan Schröer. See this page.### Wonder afternoon

13 December, Delft. Aula, lecture room B.- 13.00-13.45: Coffee/tea
- 13.45-15.30: Lectures on the work of Abel prize winner 2012 Pierre Deligne
- 13.45-14.30: Frans Oort,
*Pierre Deligne and his proof of the Weil conjectures, part I* - 14.45-15.30: Ben Moonen,
*Pierre Deligne and his proof of the Weil conjectures, part II*

- 13.45-14.30: Frans Oort,
- 15.30-16.00: Coffee/tea
- 16.00-16.30: Award ceremony of the Stieltjes Prize for the best Mathematics PhD thesis in the Netherlands in 2012 to dr Sonja Cox (ETHZ), on behalf of the Foundation Compositio Mathematica:
- Laudation by the chair of the selection committee, Michel Dekking
- Award by rector of the TUD, Prof Ir Karel Luyben

- 16.30-17.00: Lecture by Stieltjes Prize winner
- 17.00-18.00: Reception (location: "Frans van Hasseltzaal")