## 2012

### Intercity Number Theory Seminar

16 March, CWI Amsterdam. room L016- 12:00–12:45
- Hendrik Lenstra, The transfer map and determinants
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.
- 13:45–14:30
- Hendrik Lenstra, Groups generated by pseudoreflections
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.
- 14:45–15:30
- Maarten van Pruijssen, Multiplicity free systems
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.
- 15:45–16:30
- Jan-Hendrik Evertse, Effective results for unit equations over finitely generated domains

### Intercity number theory seminar

13 April, Eindhoven. Auditorium building, room 1.This meeting is the day after the NMC 2012 featuring the Beeger lecturer. There will be tea at 15:20.

- 11:00–11:50
- Yuri Bilu, Effective Diophantine analysis on modular curves
- 12:00–12:50
- Mohamed Barakat, Ext-Computability of the category coherent sheaves on a projective scheme.
- 13:30–14:20
- Viktor Levandovskyy, Stratification of affine spaces, arising from Bernstein-Sato polynomials
- 14:30–15:20
- Emil Horobet Universitatea Babes-Bolyai, Basic algebra of a skew group algebra
- 15:40–16:30
- Daniel Robertz, Implicitization of Parametrized Families of Analytic Functions

### RISC / Intercity number theory seminar

27 April, CWI Amsterdam. RoomL016. This day is focused on*fully homomorphic encryption*.

- 12:00–12:45
- Vadim Lyubashevsky, Ideal Lattices and FHE, part 1
- 13:45–14:30
- Vadim Lyubashevsky, Ideal Lattices and FHE, part 2
- 14:45–15:30
- Erwin Dassen, Brakerski's scale invariant homomorphic scheme
- 15:45–16:30
- Alice Silverberg, Some Remarks on Lattice-based Fully Homomorphic Encryption

### Intercity Number Theory Seminar

11 May, Leiden. Room 407- 11:45–12:30
- Michiel Kosters, Futile algebras
- 13:30–14:15
- Andrea Siviero Leiden, Equidistribution of the Galois module structure of rings of integers with given local behavior
- 14:30–15:15
- Ronald van Luijk, Density of rational points on Del Pezzo surfaces of degree one.
- 15:30–16:15
- Alberto Gioia, On a Galois closure for rings

### Intercity Number Theory Seminar

25 May, Groningen. Bernoulliborg, room 267- 11:45–12:45
- Anneroos Everts Groningen, From finite automata to power series and back again
- 13:30–14:30
- Paul Helminck Groningen, Tropical elliptic curves and
*j*-invariants - 14:45–15:45
- Wilke Trei Carl von Ossietzky University Oldenburg, Elliptic Curve Arithmetic on Vectorized Hardware Platforms
- 16:00–17:00
- Arthemy Kiselev Groningen, The deformation quantisation problem for multiplicative structures on noncommutative jet spaces.

### Intercity Number Theory Seminar

8 June, Utrecht. The lectures are in the Buys Ballot building, the first one in room 001 and the others in room 161- 11:15–12:15
- Peter Stevenhagen, Galois groups as arithmetic invariants
- 13:00–13:30
- Frans Oort, Lifting Galois covers of algebraic curves.
- 13:45–14:45
- Andrew Obus, Proof of the Oort Conjecture
- 15:15–16:15
- Eric Delaygue, Integrality of the Taylor coefficients of mirror maps

### Belgian-Dutch algebraic geometry day

15 June, Leuven. The lectures will take place in**Huis Bethlehem, Schapenstraat 34**in the historical centre of Leuven, within walking distance from the train station. There will be coffee at 15:00 and 16:30

- 14:00–15:00
- Ted Chinburg, Small generators for
*S*-arithmetic groups - 15:30–16:30
- Mathieu Romagny, Models of groups schemes of roots of unity
- 16:45–17:45
- Mircea Mustaţă, Adjoint line bundles in positive characteristic

### Intercity Number Theory Seminar

28 September, Leiden. Snellius building, first lecture in room B01 and the others in room 405.- 11:30–12:30
- David Holmes Leiden, Explicit Arakelov theory for Néron-Tate heights on the Jacobians of curves
- 13:30–14:15
- Michiel Kosters Leiden, Generating the rational points of an elliptic curve over
**F**_{q}by looking at*x*-coordinates - 14:45–15:45
- Maarten Derickx Leiden, Torsion points on elliptic curves over number fields of degree 5, 6 and 7.
- 16:00–17:00
- Marco Streng VU Amsterdam, Smaller class invariants for quartic CM-fields

### Intercity Number Theory Seminar

19 October, Utrecht. Uithof, Buys Ballot Lab (BBL) room 169.- 13:30–14:30
- Johan Bosman Utrecht, Ranks of elliptic curves with prescribed torsion over number fields
- 15:00–16:00
- Sander Dahmen Utrecht, Some generalized Fermat equations of signature (p,p,q)
- 16:15–17:15
- Frits Beukers Utrecht, Divisibility sequences among linear recurrent sequences

### Springer Day

26 October, Utrecht. A day in memory of Tonny Springer, see the website for programme and registration.### Intercity Number Theory Seminar

2 November, Eindhoven. Room MF 3.119 in the new building called Metaforum.- 11:00–12:00
- Patrik Norén Aalto, Volumes in algebraic statistics
- 13:00–14:00
- Rob Eggermont Eindhoven, Degree bounds on tree models
- 14:20–15:20
- Piotr Zwiernik Eindhoven, Graphical Gaussian models and their groups
- 15:20–16:20
- Jan Draisma Eindhoven, Maximum likelihood duality for determinantal varieties

### Intercity Number Theory Seminar

9 November, Groningen. Bernoulliborg, room 267- 11:45–12:45
- Afzal Soomro Groningen, Maximal curves of genus one and two, and twists
- 13:30–14:30
- Osmanbey Uzunkol Oldenburg, Theta functions and class fields
- 14:45–15:45
- Ane Anema Groningen, Field extensions over which an elliptic curve reaches the Hasse bound
- 16:00–17:00
- Max Kronberg Oldenburg, Torsion subgroup of two dimensional abelian varieties with real multiplication

### Intercity Number Theory Seminar

16 November, VU Amsterdam. The first lecture is in F640 of the W&N building, the other lectures are in MF-FG1, in the basement of the medical sciences building.- 11:30–12:30
- Rob de Jeu VU Amsterdam, The syntomic regulator for K_4 of curves
- 13:30–14:30
- James Lewis University of Alberta, Regulators of Algebraic Cycles
- 14:45–15:30
- François-Renaud Escriva VU Amsterdam, Point counting and cup product computations
- 16:00–17:00
- Deepam Patel VU Amsterdam, Motives arising from higher homotopy theory

### DIAMANT symposium, special afternoon on algebra and number theory in cryptography

30 November, Doorn. Part of the Diamant symposium, which runs from Thursday to Friday.### 2nd Belgian-Dutch Algebraic Geometry Day

7 December, UvA Amsterdam. Room A1.10 at Amsterdam Science Park.- 13:30–14:30
- Andrei Caldararu U. of Wisconsin, Derived intersections
- 15:00–16:00
- Eduard Looijenga Utrecht, Cohomological dimension of moduli spaces of curves
- 16:30–17:30
- Daniel Huybrechts Bonn, Cycles on K3 surfaces