Density problems in Arithmetic
Problèmes de densité en Arithmétique

3 – 7 April 2023

Scientific Committee 
Comité scientifique

Chantal David (Concordia University)
Ronald van Luijk (Leiden University)
Francesco Pappalardi (Roma Tre University)
Antonella Perucca (Université du Luxembourg)
René Schoof (University of Rome Tor Vergata)


Organizing Committee
Comité d’organisation

Samuele Anni (Aix-Marseille Université)
Peter Stevenhagen (Leiden University)
Jan Vonk (Leiden University)

ln this workshop, we will consider variants of Artin’s primitive root conjecture leading to the study of the Galois groups of various radical extensions. Beyond the case of the multiplicative group studied by Lenstra and others, there are now also interesting results for elliptic radicals, and for division points in more general abelian varieties. ln this context, the elliptic analogue of Artin’s conjecture is the Lang-Trotter conjecture, which is still open after more than 40 years.
The Galois representations associated to various division points in abelian varieties are central to understanding the Galois groups of the radical extensions that one tries to explicitly describe in this context, as they control the behaviour of the primes in the underlying problems. Understanding these Galois representations, and the entanglement between the extensions generated by different prime-power radicals, is essential to progress in this area.
ln this circle of problems and questions, one encounters interesting restrictions to local-global principles that will be addressed in this workshop, not only in the context of radical extensions.


Francesco Campagna (Leibniz University Hannover)
Stephanie Chan (University of Michigan)
Nathan Jones (University of Illinois Chicago)
Emmanuel Kowalski (ETH Zurich)
Peter Koymans (Max Planck Institute for Mathematics Bonn)
Ekin Ozman (Bogazici University)
Carlo Pagano (University of Glasgow)
Eugenia Rosu (University of California Berkeley)