## 2010

### Intercity number theory seminar

5 February, Leiden. Room 405- 12:15–13:00
- Peter Bruin, Computing in Picard groups of projective curves over finite fields, part 1
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.
- 14:00–14:45
- Peter Bruin, Part 2
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.
- 15:00–15:45
- Lenny Taelman EPFL Lausanne, Towards a characteristic p analogue of the class number formula, part 1
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.
- 16:00–16:45
- Lenny Taelman EPFL Lausanne, Part 2

### Intercity number theory seminar

5 March, Utrecht. Buys Ballot Lab, room 205. There will be tea at 15:20.- 11:30–12:20
- Oliver Lorscheid Bonn, Geometry over the field with one element: an introduction
- 13:30–14:20
- Nikolas Akerblom NIKHEF, Solitons and generalized elliptic functions
- 14:30–15:20
- Guyan Robertson Newcastle, Building centralizers in
*A*_{2}~ groups - 15:40–16:30
- Dajano Tossici Scuola Normale Superiore di Pisa, On the essential dimension of group schemes in positive characteristic

### Intercity number theory seminar

19 March, Groningen. Room 267 Bernoulliborg- 11:45–12:45
- Bas Heijne Groningen, Elliptic Delsarte surfaces
- 13:30–14:30
- Jan Draisma, A tropical proof of the Brill-Noether theorem
- 14:45–15:45
- Jaap Top, Legendre elliptic curves over finite fields
- 16:00–17:00
- Mirjam Dür, On the cones of completely positive and doubly nonnegative matrices and their use in optimization

### Intercity number theory seminar

16 April, Leiden. Room 409- 11:15–12:00
- Ronald van Luijk, Computing Picard groups
- 12:15–13:00
- Bart de Smit, Deformation rings of group representations
- 14:00–14:45
- Michiel Kosters Leiden, Tameness and rings of integers
- 15:00–15:45
- Sep Thijssen Nijmegen, Recognizing radical extensions of prime degree
- 16:15–17:00
- Peter Stevenhagen, Primitive roots and arithmetic progressions

### Intercity number theory seminar

7 May, KNAW Amsterdam. Part of a 2 day workshop on cryptography and lattices.### Intercity number theory seminar

21 May, Utrecht. Buys Ballot Lab, room BBL 065- 11:30–12:20
- Noriko Yui Queens, The modularity of certain K3-fibered Calabi-Yau threefolds over
**Q** - 13:30–14:20
- Esther Bod Utrecht, Algebraicity of the Appell-Lauricella and Horn functions
- 14:30–15:20
- Bart de Smit, The covering spectrum of Riemannian manifolds
- 15:40–16:30
- Gunther Cornelissen, Some Dirichlet series in Riemannian geometry

### Intercity number theory seminar

11 June, Leiden. Part of the workshop on numeration at the Lorentz Center- 09:30–10:30
- Mark Pollicott, Dynamical Zeta Functions Revisited
- 11:00–12:00
- Mike Keane Wesleyan, Numeration dynamincs
- 13:00–14:00
- Vilmos Komornik, Expansions in noninteger bases
- 14:30–15:30
- Boris Adamczweski, Automata in Number Theory
- 15:30–16:30
- Shigeki Akiyama, What is the Pisot conjecture?

### Intercity number theory seminar

3 September, Leiden. Room 174- 11:30–12:30
- Lenny Taelman, Mass formulas for finite
*p*-groups - 13:30–15:30
- Andrea Lucchini Padova, The probabilistic zetafunction of finite and profinite groups
- 15:45–16:45
- Hendrik Lenstra, Radical Galois groups

### Intercity number theory seminar

17 September, Eindhoven. DIAMANT seminar room (HG 9.41).Tea and cookies will be served at 15:15

- 11:45–12:30
- Wouter Zomervrucht Leiden, The complexity of Buchberger's algorithm
- 13:30–14:15
- Jan Draisma, Gröbner bases in infinitely many variables, or equations for the 2-factor model
- 14:30–15:15
- Christiane Peters, Wild McEliece
- 15:45–16:30
- Yael Fleischmann Eindhoven, Questions of rationality in Ruan's conjecture on crepant resolutions

### Intercity number theory seminar

1 October, Nijmegen. The first talk will be in room HG00.086 and the last two talks in room HG00.071. This is also the day of the Wiskundetoernooi.- 14:30–15:15
- Cecilia Salgado, Zariski density of rational points on del Pezzo surfaces of low degree
- 15:30–16:15
- Rajender Adibhatla Essen, Higher congruence companion forms
- 16:30–17:15
- David Gruenewald, Explicit Complex Multiplication in Genus 2

### Intercity number theory seminar

15 October, CWI Amsterdam. Room L017- 14:00–14:45
- Alexander Kruppa CWI, The factorization of RSA768
- 15:00–15:45
- Florian Luca, Multiperfect repdigits
- 16:00–16:30
- Herman te Riele, Rules for construction of amicable pairs
- 16:45–17:30
- Gabriele Dalla Torre, Digits and powers of two

### Intercity number theory seminar

29 October, Leiden. Final day of the workshop Arithmetic of Surfaces at the Lorentz Center.### RISC/Intercity Number Theory Seminar

18 November, CWI Amsterdam. Special two day seminar on towers of function fields including lectures of Garcia and Stichtenoth.### DIAMANT Symposium

26 November, Lunteren. Two day workshop with a special session on the ABC conjecture on Friday afternoon. Speakers: Masser, Oesterlé, Palenstijn.### Intercity number theory seminar

10 December, Groningen. Room 293 Bernoulliborg,Speakers: Monique van Beek, Peter Dickinson, Florian Hess, Claus Diem

- 11:45–12:45
- Monique van Beek Groningen, The rank of elliptic curves admitting a 3-isogeny
- 13:30–14:30
- Claus Diem, On the discrete logarithm problem in elliptic curves.
- 14:45–15:45
- Peter Dickinson, Linear-time checking of sparse matrices for complete positivity
- 16:00–17:00
- Florian Hess, The Tate-Lichtenbaum pairing and applications