January 30, 2024
Title: Log torsors, torsion of Jacobians and models of torsors. (MI talk)
Speaker: Sara Mehidi
Log geometry was introduced in the late 1980s by Fontaine-Illusie, Deligne-Faltings and K. Kato, among others, mainly to address two fundamental and interrelated problems in algebraic geometry: compactification and degeneration. Roughfly speaking, a log scheme is a scheme which, in addition, keeps track of a "boundary".
On the other hand, the problem of extending fppf torsors has been largely encountered in the literature, without giving a satisfactory solution in the classical setting. It turns out that the additional structure that one considers to define a log scheme allows to enlarge the category of fppf torsors by defining log torsors. In particular, this provides a new framework for studying the problem of extending torsors, presenting a fresh perspective on the question.
In this talk, we will be discussing about log schemes, log torsors, models of torsors.... We intend to end up with concrete computations to illustrate our contribution on the question.