SEMINARIO
DI MATEMATICA
ore 15.00
Scuola Normale
Superiore
Pisa
(Aula
Fermi)
Zinovy
Reichstein
University
of British Columbia, Canada
Terrà un
seminario dal titolo:
“Versal
torsors with a twist”
Abstract:
Let G
be a linear algebraic group acting on an algebraic variety X. Informally
speaking, this action is versal if every G-torsor over a field can be obtained
by specialization from X. Here the term “versal” is best understood by
subtracting “unique” from both sides of the formula UNIVERSAL = UNIQUE + VERSAL.
The notion of versality and its variants play an important role in Galois
theory, in the theory of central simple algebras and in the theory of quadratic
forms. In this talk, based on joint work with Alex Duncan, I will address the
following ”recognition problem”: Determine whether or not a given G-action is
versal. The main idea is to relate versality to existence of rational points on
certain twisted forms of X. I will state a versality criterion based on this
idea and discuss a number of applications.
Tutti gli
interessati sono invitati a partecipare.
Classe
di Scienze