## Besøksadresse

Ullevål StadionSognsveien 77B

0855 OSLO

Tid og sted:
28. feb. 2018 10:15 - 12:00,
Desolation Row Sognsveien 77B

Tid og sted:
28. feb. 2018 10:15 - 12:00,
Desolation row

Tid og sted:
28. feb. 2018 09:30 - 11:00,
Ullevål Stadion: End of the Line

Shiqi Song (University of Evry Val d'Esssone, France) will give a minicourse with the title: Topics on defaultable market and on default valuation

Tid og sted:
27. feb. 2018 13:15,
Ullevål Stadion: Gates of Eden

M.Sc. Lisa Smith ved Matematisk institutt vil forsvare sin avhandling for graden ph.d.:

**Experiments of Breaking Waves in Pipes and Flumes**

Tid og sted:
27. feb. 2018 10:15 - 12:00,
End of the line

Tid og sted:
27. feb. 2018 10:15,
Ullevål Stadion: Gates of Eden

M.Sc. Lisa Smith ved Matematisk institutt avholder prøveforelesning over oppgitt emne: "Recent advances in medical imaging".

Tid og sted:
27. feb. 2018 09:30 - 11:00,
Ullevål Stadion: Hurricane

Tid og sted:
21. feb. 2018 14:15 - 16:00,
Desolation Row, Sognsveien 77B

I will review Marcel Bökstedt's calculation of the topological Hochschild homology of prime fields and the integers, taking into account simplifications made in papers by Angeltveit-R. (where BP<m-1> specializes to HFp for m=0 and to HZ(p) for m=1) and Ausoni (proof of Lemma 5.3).

Tid og sted:
21. feb. 2018 11:15 - 12:00,
Seminar room "End of the Line"

**Speaker:** Giuseppe Coclite (University of Bari)

**Title:** Nonlinear Peridynamic Models

**Abstract:** Some materials may naturally form discontinuities such as cracks as a result of scale effects and long range interactions. Peridynamic models such behavior introducing a new nonlocal framework for the basic equations of continuum mechanics. In this lecture we consider a nonlinear peridynamic model and discuss its well-posedness in suitable fractional Sobolev spaces. Those results were obtained in collaboration with S. Dipierro (Milano), F. Maddalena (Bari) and E. Valdinoci (Milano).

Tid og sted:
21. feb. 2018 10:15 - 12:00,
Desolation Row Sognsveien 77 B

Inspired by the Voevodsky machinery of standard triples a machinery of nice triples was invented in [PSV]. We develop further the latter machiny such that it works also in the finite field case [P]. This machinary is a tool to prove many interesting moving lemmas. It leads to a serios of applications. One of them is a proof of the Grothendieck--Serre conjecture in the finite field case. Another is a proof of Gersten type results for arbitrary cohomology theories on algebraic varieties. The Gersen type results allows to conclude the following: a presheaf of S1-spectra E on the category of k-smooth schemes is A1-local iff all its Nisnevich sheaves of stable A1-homotopy groups are strictly homotopy invariant. If the field k is infinite, then the latter result is due to Morel [M]. An example of moving lemma is this. Let X be a k-smooth quasi-projective irreducible k-variety, Z be its closed subset and x be a finite subset of closed points in X. Then there exists a Zariski open U containing x and a naive A1-homotopy between the motivic space morphism U--> X--> X/U and the morphism U--> X/U sending U to the distinguished point of X/U. Application: suppose E is a cohomology theory on k-smooth varieties and alpha is an E-cohomology class on X which vanishes on the complement of Z, then it vanishes on U from the lemma above.

Tid og sted:
21. feb. 2018 10:15 - 12:00,
Desolation row

Tid og sted:
14. feb. 2018 15:15 - 16:00,
End of the line, Ullevål Stadion

Soft and Wet is Different

Tid og sted:
14. feb. 2018 14:15 - 16:00,
Desolation Row Sognsveien 77B

In this second talk, I will define Chekanov's version of Legendrian contact homology (LCH) for Legendrian knots in R3. I will begin with an example, showing that LCH is more sensitive than the classical invariants. This will use a linearized version of the homology. In the second part of the talk I will focus on the proof that the differential indeed squares to zero, and also say something about invariance under Legendrian Reidemeister moves. This is intended to be a smooth introduction to the next talk, where we will consider Legendrian contact homology defined for Legendrians in arbitrary 1-jet spaces. This case is more delicate, and we have to understand the concept of Gromov compactness for pseudo-holomorphic curves to prove that we get a differential graded algebra associated to each Legendrian, whose homology will give a Legendrian invariant.

Tid og sted:
14. feb. 2018 10:15 - 12:00,
Desolation Row Sognsveien 77B

Let G be a finite (abstract) group and let k be a field of characteristic zero. We prove that for a non-singular projective G-variety X over k, and a non-singular G-invariant subvariety Y of dimension >= 3, which is a scheme-theoretic complete intersection in X, the pullback map PicG(X) -> PicG(Y) is an isomorphism. This is an equivariant analog of the Grothendieck-Lefschetz theorem for Picard groups.

Tid og sted:
14. feb. 2018 10:15 - 12:00,
Desolation row

Tid og sted:
9. feb. 2018 09:00 - 10:00,
Seminarrom 108

Nytt semester har startet. Vi lurer på hvordan det går med deg. Kom og få gratis kaffe og mat på seminarrom 108. / New semester has started. We wonder how you are. Come to the seminar room 108 and get free coffee and food.

Tid og sted:
7. feb. 2018 14:15 - 16:00,
Desolation Row Sognsveien 77B

A Cartan-Eilenberg system is an algebraic structure introduced as a model of the diagram obtained by taking the homology of all subquotients in a filtered chain complex. There are two exact couples and a single spectral sequence associated with such a system, and one may thus apply Boardman's theory of convergence to either exact couple. After reviewing parts of this theory, I will clarify the convergence situation in a Cartan-Eilenberg system and in particular present new work on a simpler interpretation of Boardman's whole plane obstruction group.

Tid og sted:
6. feb. 2018 11:00 - 12:00,
Gates of Eden

Zahra Afsar (University of Wollongong, Australia) will give a talk with title: Nica-Toeplitz-algebras of *-commuting local homeomorphisms and equilibrium states

Abstract: Given a family of *-commuting local homeomorphisms on a compact space, we can build a compactly aligned product system of Hilbert bimodules. The product system has a Nica-Toeplitz algebra which carries a gauge action of a higher-dimensional torus, and there are many possible dynamics obtained by composing with different embeddings of the real line in this torus. In this work, which is a joint work with Prof. Astrid an Huef and Prof. Iain Raeburn, I will talk about the equilibrium states of these dynamics. If time allows, I will also provide some examples from higher rank graph theory and reconcile our results with those existing ones.

Tid og sted:
1. feb. 2018 14:30 - 15:30,
Gates of Eden, Sognsv. 77B

**Abstract:**

If X is a compact metric space, then a measure on X is a linear, bounded and positive operator on the space of continuous functions on X. If f:X->Y is a continuous map between compact metric spaces, then by tautology we can pushforward any measure on X. Can we pullback a measure? No answer had been found in the literature.

In this talk I will explain why we cannot pullback a measure to a measure in general, even in the case where f is an isomorphism over a dense open subset of Y. On the other hand, I will show that if f is a finite covering over a dense open subset of Y, then we can pullback any measure on Y to a more general class of so-called positive strong submeasures. This is then applied to dynamics of meromorphic maps of compact Kahler manifolds. This general class of strong submeasures can also be used in the problem of intersection of hypersurfaces.

NB! Coffee/Tea/Biscuits from 14.00.

Tid og sted:
31. jan. 2018 14:15 - 16:00,
Desolation Row, Sognsveien 77 B

I will give a series of talks about Legendrian contact homology, an invariant of Legendrian submanifolds in 1-jet spaces, defined by a count of pseudo-holomorphic curves. In this first lecture I will give a brief and gentle introduction to symplectic and contact geometry, with focus on Lagrangian and Legendrian submanifolds. No previous knowledge about the subject is needed, except for elementary knowledge about differentiable manifolds.

Tid og sted:
31. jan. 2018 11:15 - 12:00,
Seminar room "End of the Line" (2nd floor), Sognsveien 77B, Ullevål Stadion

Tid og sted:
24. jan. 2018 11:15 - 12:00,
Seminar room "End of the Line" (2nd floor), Matematisk Institutt, Sognsveien 77B, Ullevål Stadion

Tid og sted:
19. jan. 2018 13:15,
"Hurricane", Ullevål stadion, Sognsveien 77 B.

Tittel:

**Computational Analysis of a Drag reducing Cone Grid**

*A finite volume simulation of the gecko's aerodynamic skin*