Séminaire de l’équipe AGA
Responsables : F. SCAVIA, M. TAMIOZZO
Vendredi 6 février 2026
10:30 Jesse Pajwani (University of Bristol) 
Résumé
Motivic Invariants of Automorphisms
Salle B407, bâtiment B, LAGA, Institut Galilée, Université Paris 13When doing arithmetic geometry, it is helpful to have invariants of the objects which we are studying that see both the arithmetic and the geometry. Motivic homotopy theory allows us to produce new invariants which generalise classical topological invariants, such as the Euler characteristic of a variety. These motivic invariants not only recover the classical topological ones, but also provide arithmetic information. In this talk, I'll review the construction of a motivic Euler characteristic, then study its arithmetic properties, and mention some applications. I'll then talk about work in progress with Ran Azouri, Stephen McKean and Anubhav Nanavaty which studies a "higher Euler characteristic", allowing us to produce an invariant of automorphisms valued in an arithmetically interesting group. I'll then talk about how to relate part of this invariant to a more classical invariant of quadratic forms.
Vendredi 13 février 2026
10:30 Andrew Graham (University of Oxford)
Titre bientôt disponible
Salle B407, bâtiment B, LAGA, Institut Galilée, Université Paris 13
Vendredi 20 février 2026
10:30 Theodosis Alexandrou (Humboldt-Universität)
Titre bientôt disponible
Salle B407, bâtiment B, LAGA, Institut Galilée, Université Paris 13
Vendredi 27 février 2026
10:30 Mattia Cavicchi (Université Bourgogne Europe)
Titre bientôt disponible
Salle B407, bâtiment B, LAGA, Institut Galilée, Université Paris 13
