## 2007

- February 2 and 9: DIAMANT postdoc intercity in Eindhoven
- February 23: Crystallography in Nijmegen

### Intercity Number Theory Seminar

16 March, Utrecht. Room 202 Minnaert- 11:30–12:30
- Jaap Top, Elliptic surfaces with a high Picard number
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.
- 13:15–13:45
- Nguyen Khuong An, Groningen), The algebraic subgroups of GL
_{2}(**C**).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
- Marius van der Put, Solving linear differential equations
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.
- 15:15–16:15
- Steve Meagher, Freiburg), When is the twist of a Jacobian a Jacobian?
- 16:30–17:00
- Lenny Taelman, An exercise in algebraic topology

### DIAMANT Intercity Number Theory Seminar

30 March, Leiden. room 405. Joint session with RISC seminar (CWI)- 11:00–11:45
- Peter Montgomery, Parallel block Lanczos
- 12:00–12:45
- Ramarathnam Venkatesan, Microsoft Research), Cryptographic applications involving Spectral analysis of Rapid mixing
- 13:45–14:30
- Corentin Pontreau, Bogomolov's problem, small points on varieties
- 14:45–15:30
- Sierk Rosema, Leiden), Sturmian substitutions, cutting paths and their projections

### Intercity Number Theory Seminar

25 May, Leiden. The first talk will be in the Sitter room (ground floor of the Oort building), and the other talks will be in room 204 of the Huygens building (directions)- 12:00–13:00
- David Kohel, Complex multiplication and canonical lifts
- 14:00–15:45
- Johan Bosman, A polynomial with Galois group SL
_{2}(**F**_{16}) - 16:00–17:00
- Reinier Bröker, Lifting supersingular curves

### Intercity Number Theory Seminar

8 June, Utrecht. Room 211 Minnaert buildingTea with cookies will be served at 15:10.

- 11:00–12:00
- Harm Voskuil,
*p*-Adic uniformisation: introduction and examples - 13:00–14:00
- Fumiharu Kato, Topological rings in rigid geometry
- 14:10–15:10
- Francis Brown, Multiple zeta values and periods of moduli spaces of genus zero curves
- 15:30–16:30
- Gautam Chinta, The theory of Weyl group multiple Dirichlet series

### GTEM day

21 September, Leiden. Special day of lectures at the GTEM workshop at the Lorentz Center (room 201 Huygens)- 11:00–11:45
- Dieter Geyer, Higher dimensional class field theory
- 12:00–12:45
- Andrea Surroca Ortiz, On the Mordell-Weil and the Tate-Shafarevich groups of abelian varieties
- 14:00–14:45
- Christian Wuthrich, Computations about the Tate-Shafarevich group using Iwasawa theory
- 15:00–15:45
- Gabor Wiese, Modular Forms in Inverse Galois Theory

### Intercity Number Theory Seminar

5 October, Delft. Snijderszaal op de 1e etage EWI gebouw, Mekelweg 4, DelftBereikbaar via bus 129 vanaf Delft CS

Parkeerplaats achter het gebouw

There is a group lunch for the seminar participants, and there will be tea and coffee at 14:30

- 11:30–12:30
- Graham Everest, Elliptic Curves and Hilbert's tenth problem
- 13:30–14:30
- Karma Dajani, Ergodic properties of signed binary expansions
- 14:45–15:45
- Fritz Schweiger, Multidimensional continued fractions - new results and old problems

### RISC / INTS: Computational Number Theory

19 October, CWI Amsterdam. Lectures in room Z009 (ground floor)- 12:00–13:00
- Ronald van Luijk, Explicit twisting of Jacobians of dimension 2
- 14:00–15:00
- Alexander May, Bochum), Using LLL-Reduction for Solving RSA and Factorization Problems: A survey
- 15:15–16:15
- David Freeman, Constructing abelian varieties for pairing-based cryptography

### Intercity Number Theory Seminar

9 November, VU Amsterdam.**Room change**: the first lecture will take place in room Q105, the second in room C147, and the third in Q112. All rooms are in the "W&N gebouw", number 1081 on this map.

- 12:00–12:45
- Rob de Jeu, Part I: introduction to
*K*_{0},*K*_{1},*K*_{2} - 13:30–14:15
- Rob de Jeu, Part II:
*K*_{2}of curves over number fields - 14:30–16:15
- Hendrik Lenstra, Algorithms for ordered fields

### Special day on discrete tomography

23 November, Leiden. Room 403. Tentative program:- 11:45–12:30
- Rob Tijdeman, Words with any periods
- 13:30–14:15
- Sierk Rosema, Leiden), Beta-substitutions, cutting paths and their projections
- 14:30–15:30
- Birgit van Dalen, Dependencies between line sums
- 15:45–16:45
- Arjen Stolk, An algebraic approach to line sum dependencies

### Intercity Number Theory Seminar

7 December, Utrecht. The first talk will be in room BBL 160 (Buys Ballot Lab, Uithof), the others in BBL 105.- 11:00–12:00
- Victor Abrashkin, Durham), An elementary approach to Breuil's classification of finite flat
*p*-group schemes - 13:00–14:00
- Cameron Stewart, On a refinement of the
*ABC*conjecture - 14:10–15:00
- Frits Beukers, Nearby perfect powers
- 15:30–16:30
- Attila Bérczes, On pairs of polynomials and binary forms with given resultant

### Special day on cryptology

21 December, Leiden. The first two talks will be in room 174. The inaugural lecture of Ronald Cramer will take place in the Poortgebouw, Rijsburgerweg 10, Leiden (see map). To attend this lecture, please register here and be present 10 minutes in advance. This day is organized jointly with the RISC seminar.- 11:30–12:30
- Ivan Damgaard, The Past, Present and Future of Secure Multi-Party Computation
- 13:30–14:30
- Yuval Ishai, Secure Multi-Party Computation in the Head
- 16:15–17:15
- Ronald Cramer, Inaugural lecture (in Dutch)