# Seminars

## Upcoming

Time: May 14, 2018 - May 18, 2018

Paul Arne Østvær will speak at the conference Motivic homotopy theory and refined enumerative geometry at the Universität Duisburg-Essen, Essen, Germany on "A motivic Segal conjecture for the group of order two."

Time and place: May 29, 2018 10:00 AM - May 30, 2018 1:00 PM,

On the 29th and 30th of May, a topology meeting will convene at the University of Oslo to discuss a broad range of topics in topology, including topological Hochschild homology, motivic homotopy theory, symplectic geometry, and low-dimensional geometry.

Time: May 31, 2018 9:30 AM - 10:20 AM

Sabrina Pauli will speak at the conference Algebraic Geometry - Mariusz Koras in memoriam at the Institute of Mathematics, Polish Academy of Sciences on "A1-contractibility of Koras-Russell like varieties."

Time: June 1, 2018 - July 31, 2018

Paul Arne Østvær will hold a lecture series as a Nelder visiting fellow at the Imperial College London during June and July of 2018.

Time: July 4, 2018 2:30 PM - 3:30 PM
Time: July 9, 2018
Time: July 23, 2018 10:15 AM - July 27, 2018 12:00 PM

Charanya Ravi will speak at K-Theory Workshop, a satellite event of the ICM 2018.

Time: Aug. 6, 2018 2:45 PM - 3:30 PM
Time: Sep. 10, 2018

Paul Arne Østvær will speak at the conference Motives and their applications, at the Euler International Mathematical Institute in St. Petersburg.

## Previous

Time: Mar. 26, 2018 10:15 AM - Mar. 30, 2018 12:00 PM

Paul Arne Østvær will speak at the conference Motives in Tokyo, which will be held in honor of Shuji Saito's 60th birthday.

Time and place: Mar. 20, 2018 10:15 AM - 12:00 PM, End of the line

This talk is supposed to be an Introductionary talk to the preprint arXiv:1409.4372v4 (joint work with G.Garkusha). More specifically, using the theory of framed correspondences developed by Voevodsky, the authors introduce and study framed motives of algebraic varieties. This study gives rise to a construction of the big frame motive functor. It is shown that this functor converts the classical Morel--Voevodsky motivic stable homotopy theory into an equivalent local theory of framed bispectra, and thus producing a new approach to stable motivic homotopy theory. As a topological application, it is proved that for the simplicial set $Fr(Delta^\bullet_C, S^1)$ has the homotopy type of the space $\Omega^{\infty} Sigma^{\infty} (S^1)$. Here C is the field complex numbers.

Time and place: Mar. 14, 2018 10:15 AM - 12:00 PM, Desolation row
Time and place: Mar. 13, 2018 11:15 AM - 12:00 PM, End of the line

In this talk, we will present a relation between the classical Chow group of relative 0-cycles on a regular scheme X, projective and flat over an excellent Henselian discrete valuation ring A with perfect residue field k, and the so-called cohomological Chow group of zero cycles of the special fiber. If k algebraically closed and with finite coefficients (prime to the residue characteristic) these groups turn out to be isomorphic. This generalizes a previous argument due to Esnault-Kerz-Wittenberg to the case of regular models with arbitrary reduction. From this, one can re-prove in case of bad reduction that the étale cycle class map for relative 0-cycles with finite coefficients on X is an isomorphism, a result due to Saito and Sato in the case of semi-stable reduction. This is a joint work with Amalendu Krishna.

Time and place: Mar. 13, 2018 10:15 AM - 11:00 AM, End of the line

Grothendieck invented the category of numerical motives. From this, the abelian category of pure motives can be obtained assuming his conjectures. This category serves as a universal cohomology theory for schemes smooth and projective over a field. It is expected that there is an abelian category of mixed motives, which contains the abelian category of pure motives as a full subcategory and serves as a universal cohomology theory for schemes smooth but not necessarily projective over a field. I will explain how mixed motives looks assuming several conjectures, and I will give some unconditional examples including 2-motives.

Time and place: Mar. 7, 2018 10:15 AM - 12:00 PM, Desolation row
Time and place: Mar. 6, 2018 10:15 AM - 12:00 PM, End of the Line

Recently two different refinements of Voevodsky's theory of presheaves with transfers were introduced: the first one is the theory of framed presheaves based on the unpublished notes by Voevodsky and developed by Garkusha and Panin and the second one is the theory of Milnor-Witt presheaves due to Calmes and Fasel. I will review some relations between these theories and explain that the hearts of the homotopy t-structures on the corresponding categories of motives are naturally equivalent. The talk is based on a joint work with A. Neshitov.

Time and place: Feb. 28, 2018 10:15 AM - 12:00 PM, Desolation row
Time and place: Feb. 27, 2018 10:15 AM - 12:00 PM, End of the line
Time and place: Feb. 21, 2018 10:15 AM - 12:00 PM, Desolation row
Time and place: Feb. 14, 2018 10:15 AM - 12:00 PM, Desolation row
Time: Feb. 13, 2018
Time: Dec. 12, 2017

Paul Arne Østvær will hold a seminar at the University of Osnabrück.

Time: Dec. 5, 2017 2:15 PM - 3:15 PM

Glen Wilson will hold a seminar at the Oberseminar Topologie at the University of Osnabrück.

Time: Nov. 29, 2017 2:15 PM - 3:15 PM

Glen Wilson will hold a seminar at the Wuppertal Topology Seminar.

Time: Nov. 23, 2017

Paul Arne Østvær will hold a seminar at the Oberseminar Algebra, Geometrie und Zahlentheorie at the University of Duisburg-Essen.

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