Guest lectures and seminars - Page 119
The so-called Koras-Russell threefolds are a family of topologically
contractible rational smooth complex affine threefolds which played an
important role in the linearization problem for multiplicative group
actions on the affine 3-space. They are known to be all diffeomorphic to
the 6-dimensional Euclidean space, but it was shown by Makar-Limanov in
the nineties that none of them are algebraically isomorphic to the affine
3-space. It is however not known whether they are stably isomorphic or not
to an affine space. Recently, Hoyois, Krishna and Østvær proved that many
of these varieties become contractible in the unstable A^1-homotopy
category of Morel and Voevodsky after some finite suspension with the
pointed projective line. In this talk, I will explain how additional
geometric properties related to additive group actions on such varieties
allow to conclude that a large class of them are actually A^1-contractible
(Joint work with Jean Fasel, Université Grenoble-Alpes).
Digital signalbehandling og bildeanalyse, UiO and PGS
The effects of moving rough sea surfaces on seismic data.
Andreas Andersson (UiO): An introduction to duality for compact groups in algebraic quantum field theory
Tamara Broderick (Massachusetts Institute of Technology) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.