Monday, April 12th, 2021, 16:30, on Zoom.
Thierry Coquand (Göteborg)
Sheaf models and constructive mathematics
Sheaf models over sites, introduced by Grothendieck in algebraic geometry, are also important in the meta-theory of intuitionistic mathematics for showing that some properties are not valid constructively or for providing models of the notion of choice sequences. In this talk, I would like to explain another use of sheaf models in constructive mathematics, suggested by Joyal in 1975, which is to provide a way to build an algebraic closure of an arbitrary field.
The seminar will be held on Zoom. In order to get access to the Zoom meeting, please contact Peter Schuster or Giulio Fellin.