## 2015

### RISC Seminar/Intercity Number Theory Seminar: Cryptologic Algorithms

6 February, CWI Amsterdam. Euler Room (Z009, ground floor). For abstracts, see the program.- 10:30–11:00
- Benjamin Wesolowski EPFL, Random Self-Reducibility of the Discrete Logarithm Problem in Genus 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.
- 11:15–12:00
- Rob Granger EPFL, A tale of two QPAs
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.
- 13:45–14:15
- Alina Dudeanu EPFL, Computing Denominators of Igusa Class Polynomials
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.
- 14:15–14:45
- Anja Becker EPFL, A Sieve Algorithm Based on Overlattices
- 15:00–15:30
- Joppe Bos NXP Semiconductors, Sieving for Shortest Vectors in Ideal Lattices: a Practical Perspective
- 15:45–16:30
- Arjen Lenstra EPFL, Factorization Factories

### Intercity Number Theory Seminar

20 February, Leiden. Snellius building, Room B03.- 11:30–12:30
- Peter Bruin Universiteit Leiden, Computing modular Galois representations
- 13:45–14:45
- Elisa Universiteit Leiden, A Gross-Zagier formula for dimension 3
- 15:00–16:00
- Marta Pieropan Leibniz Universität Hannover, On the distribution of rational points on Fano varieties over number fields
- 16:15–17:15
- Peter Stevenhagen Universiteit Leiden, Adelic points of elliptic curves

### Intercity Number Theory Seminar

13 March, Groningen. First two lectures in room 165, Bernoulliborg, last two lectures in room 105.- 12:00–13:00
- Ute Spreckels Oldenburg, On the primality of the order of CM abelian varieties over finite prime fields
- 13:30–14:30
- Paul Helminck Groningen, Variations on some constructions by J-F. Mestre
- 15:00–16:00
- Remke Kloosterman HU Berlin, An upper bound for the Mordell-Weil rank after Galois base change and a Chevalley-Weil formula for certain surfaces
- 16:15–17:15
- Jaap Top Groningen, Lucas-Lehmer revisited

### Seminar Aachen-Köln-Lille-Siegen (AKLS) and Intercity Number Theory Seminar

24 April, Utrecht. BBG (Buys Ballot Gebouw), room 065 (ground floor)- 14:00–15:00
- Roelof Bruggeman Utrecht, Holomorphic automorphic forms and cohomology
- 15:00–16:00
- Carel Faber Utrecht, On Teichmüller modular forms
- 17:00–18:00
- Miranda Cheng Amsterdam, UvA, Optimal mock Jacobi forms

### Intercity Number Theory Seminar

8 May, UvA and VU Amsterdam. This seminar will be held at the Vrije Universiteit. Before lunch in room WN-P647 (W&N-building), after lunch in HG-08A05 (main building).- 11:00–12:00
- Lenny Taelman UvA, Complex multiplication and K3 surfaces over finite fields
- 13:00–14:00
- Abhijit Laskar VU University Amsterdam, On local monodromy filtrations attached to motives
- 14:30–15:30
- Ada Boralevi TU Eindhoven, Linear spaces of matrices of constant rank
- 16:00–17:00
- Frits Beukers Utrecht, Finite hypergeometric functions

### Intercity Number Theory Seminar

27 May, Eindhoven. The first two talks are in Auditorium 12. The PhD defense of Rob Eggermont is in Auditorium 4.- 13:30–14:20
- Giorgio Ottaviani Firenze, The Waring decomposition of a polynomial and its uniqueness
- 14:30–15:20
- Jochen Kuttler Alberta, Modules of differentials for Lie algebras
- 16:00–17:00
- Rob Eggermont Eindhoven, PhD defense

### DIAMANT Symposium

29 May, TBA. This is a two-day event: May 28 and 29.### North German Algebraic Geometry Seminar (NoGAGS) and 8th Belgian-Dutch Algebraic Geometry Day(s)

12 June, Nijmegen. The Program. This is a two-day event: June 11 and 12.### Intercity Number Theory Seminar

25 September, Leiden. Snellius building. Morning: B2, afternoon: 407/409.- 11:30–12:30
- Christopher Frei TU Graz, The Hasse norm principle for abelian extensions
- 13:30–14:30
- Efthymios Sofos Universiteit Leiden, On the fibration method in analytic number theory
- 15:00–16:00
- Alex Bartel Warwick University, Heuristics for Arakelov class groups
- 16:15–17:15
- Maarten Derickx Universiteit Leiden, Galois closures over integrally closed domains

### Intercity Number Theory Seminar

16 October, Utrecht. Rode zaal in Ruppertgebouw, Leuvenlaan 21.- 13:00–13:45
- Martijn Kool Utrecht, Donaldson-Thomas invariants of local elliptic surfaces
- 14:00–14:45
- Gert Heckman Nijmegen, Moduli of real genus 3 curves
- 15:15–16:00
- Cor Kraaikamp Delft, Natural extensions and Nakada’s alpha-expansions
- 16:15–17:00
- Frits Beukers Utrecht, A geodesic continued fraction using LLL

### ANA2015 (Automatic Sequences, Number Theory, Aperiodic Order)

30 October, Delft. Room Pi in the EWI building. This is part of a 3-day event: please register.### Intercity Number Theory Seminar

6 November, UvA and VU Amsterdam. This seminar will be held at the Vrije Universiteit: the morning talk in HG-08A33 (main building) and the afternoon talks in WN-M607 (mathematics and physics building).- 11:15–12:15
- Arno Kret UvA, Galois representations for the general symplectic group
- 13:15–14:15
- Rob de Jeu VU, Numerical experiments for p-adic L-functions
- 14:30–15:30
- Lance Gurney UvA, Frobenius lifts and minimal models of CM elliptic curves
- 16:00–17:00
- Jan Draisma TU/e & VU, Orthogonally decomposable tensors as semisimple algebras

### DIAMANT Symposium

27 November, Lunteren. This is a two-day event: November 26-27### 9th Belgian-Dutch Algebraic Geometry Day

11 December, Leiden. Snellius Building, room 407-409, of the Maths Dept. in Leiden. Organisers: Ben Moonen, Johannes Nicaise, Lenny Taelman, Bas Edixhoven.- 13:30–14:30
- David Holmes Leiden, Models of degenerating jacobians
- 15:00–16:00
- Clément Dupont MPIM Bonn, Motives of bi-arrangements
- 16:30–17:30
- Misha Verbitsky ULB (Brussels), HSE (Moscow), Transcendental Hodge algebra

### Geometry in Winter, A memorial symposium for Prof. dr. A.H.J.M. van de Ven

18 December, Leiden. Snellius building, room 312. For more information, including abstracts, see website.- 11:00–11:45
- Ekaterina Amerik Univ. de Paris Sud, Orsay, Some applications of the cone conjecture for hyperkaehler manifolds
- 13:00–13:45
- Arnaud Beauville Univ. de Nice, Recent developments on stable rationality
- 14:00–14:45
- Fabrizio Catanese Univ. Bayreuth, Interesting Variations of Hodge Structures and related algebraic surfaces
- 15:00–15:45
- Klaus Hulek Univ. Hannover, Intermediate Jacobians of cubic threefolds and their degenerations
- 16:00–16:45
- Chris Peters Univ. Grenoble I and T.U. Eindhoven, Vector bundles and surfaces, a lifelong fascination