Gjesteforelesninger, seminarer og konferanser


Tid: 28. feb. 2017 14:15

Riccardo De Bin (Department of Mathematics, University of Oslo) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.

Tid og sted: 2. mars 2017 11:15 - 12:00, 801
Tid og sted: 7. aug. 2017 - 11. aug. 2017, Svolvær, Lofoten

The Abel symposium 2017


Tid og sted: 22. feb. 2017 14:15 - 16:00, B 738

The classical s-cobordism theorem classifies completely h-cobordisms from a fixed manifold, but it does not tell us much about the relationship between the two ends. In the talk I will present some old and new results about this. I will also discuss how this relates to a seemingly different problem: what can we say abobut two compact manifolds M and N if we know that MxR and NxR are diffeomorphic? This is joint work with Slawomir Kwasik, Tulane, and Jean-Claude Hausmann, Geneva.

Tid og sted: 22. feb. 2017 12:15 - 14:00, B 637

I will survey the connection between the space H(M) of h-cobordisms on a given manifold M, several categories of spaces containing M, Waldhausens algebraic K-theory A(M), and the algebraic K-theory of the suspension ring spectrum S[?M] of the loop space of M. The results extend the h-cobordism theorem of Smale and the s-cobordism theorem of Barden, Mazur and Stallings to a parametrized h-cobordism theorem, valid in a stable range established by Igusa, first discussed by Hatcher and finally proved and published by Waldhausen, Jahren and myself.

Tid og sted: 13. feb. 2017 14:00 - 15:00, NHA 935
Tid og sted: 13. feb. 2017 13:15 - 14:00, Niels Henrik Abels hus, room 801

Agnès Sulem (INRIA Paris) gives a lecture with the title: Game options in an imperfect financial market with default

Tid og sted: 9. feb. 2017 15:15 - 17:00, NHA room 735

Elizabeth Gillaspy, p.t. Münster (Germany) will give a talk with title "Wavelets and spectral triples for higher-rank graphs"  

Tid og sted: 6. feb. 2017 13:15 - 14:00, Niels HenrikAbels hus, room 801

Erik Bølviken (University of Oslo) gives a lecture with the title: Where models meet reality - The Solvency II regulation of  European insurance

Tid: 2. feb. 2017 10:15 - 12:00

The Oslo-Seminar in Mathematical Logic will take place at the same time and in the same location as in the previous terms.

Thursdays 10.15 - 12.00 in the meeting room of floor 9 in the computer science building.

Tid og sted: 1. feb. 2017 14:15 - 16:00, B 738

The Barratt nerve BSd X of the Kan subdivision Sd X of a simplicial set X \in sSet is a triangulation. The Barratt nerve is defined as taking the poset of non-degenerate simplices, thinking of it as a small category and then finally taking the nerve.Waldhausen, Jahren and Rognes (Piecewise linear manifolds and categories of simple maps) named this construction 'the improvement functor' because of the homotopical properties and because its target is non-singular simplicial sets. A simplicial set is said to be 'non-singular' if its non-degenerate simplices are embedded. There is a least drastic way of making a simplicial set non-singular called 'desingularization', which is a functor D:sSet -> nsSet that is left adjoint to the inclusion. The functor DSd^2 is the left Quillen functor of a Quillen equivalence where the model structure on sSet is the standard one where the weak equivalences are those that induce weak homotopy equivalences and the fibrations are the Kan fibrations. I will talk about the main steps of the proof that the natural map DSd X -> BX is an isomorphism for regular X. This implies that DSd^2 is a triangulation and that the improvement functor is less ad hoc than it may seem. Furthermore, I will explain how the result provides evidence that any cofibrant non-singular simplicial set is the nerve of some poset.   

Tid: 31. jan. 2017 14:15

Inge S. Helland (Professor emeritus at Department of Mathematics,UiO) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.

Tid og sted: 26. jan. 2017 11:00 - 28. jan. 2017 15:00, University of Oslo

A conference celebrating the work of Ragni Piene on the occasion of her 70th birthday.

Tid og sted: 10. jan. 2017 10:15 - 12:00, B 738 NHA

Triangulated categories of motives over schemes are sort of the "universal derived categories" among various derived categories obtained by various cohomology theories like l-adic cohomology. Ayoub constructed them using the A1-homotopy equivalences and étale topology. I will introduce the construction of triangulated categories of motives over fs log schemes. Fs log schemes are kinds of "schemes with toroidal boundary," and A1-homotopy equivalences and étale topology are not enough to obtain all homotopy equivalences between fs log schemes. I will explain what extra homotopy equivalences and topologies are neeeded. 

Tid og sted: 9. jan. 2017 08:30 - 10. jan. 2017 17:00, The Norwegian Academy of Science and Letters

The symposium is a follow-up of four highly successful previous symposia, held 14-15 October 2008 in the Norwegian Academy in Oslo, 1-2 November 2010 in RSE in Edinburgh, 2013 Oslo and 2015 Edinburgh.  Topics of this year's symposium include: internal waves, waves and ice, freak waves and wave-structure interaction as well as related aspects of stratified and buoyancy-driven oceanic flows. 

The scope of the programme will reflect the ongoing wave research projects in Norway and Scotland individually and in collaboration and it will include a special session celebrating the 6oth birthday of John Grue, the co-Director of the DNVA-RSE Waves symposia since their inception.



Tid og sted: 5. jan. 2017 12:00 - 8. jan. 2017 09:00, Lysebu (Oslo)

The 17th Danish-Norwegian workshop in Operator algebras will take place at Lysebu (Oslo), January 5 - 8, 2017, with support from the Foundation for Danish-Norwegian Cooperation. It will start with lunch on Thursday, January 5, and end after breakfast on Sunday, January 8.

One day of the workshop will be devoted to commemorate our dear colleague and friend, Ola Bratteli, who passed away in 2015 and would have turned 70 in October 2016.  Ola’s nearest collaborators over the years (George Elliott, David Evans, Akitaka Kishimoto, Palle Jorgensen and Derek Robinson) will then give talks reflecting the great impact of Ola’s work within several topics (e.g. AF-algebras, derivations, C*-dynamical systems, mathematical physics, wavelets).

Participation is possible only by personal invitation from the organizing committee. 

The programme will be made available around the beginning of December. 

Tid: 20. des. 2016 14:15

Daniel Roy (Department of Statistical Sciences, University of Toronto) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.

Tid og sted: 15. des. 2016 10:15 - 12:00, GHS room 3514

Ulrik Bo Rufus Enstad (Oslo) will give a talk with title: Connections between Gabor frames and Noncommutative Tori

Abstract: A Gabor frame is a special type of frame in the Hilbert space of square-integrable functions on the real line. Gabor frames provide robust, basis-like representations of functions, and have applications in a wide range of areas. They have a duality theory which is deeply linked to Rieffel’s work on imprimitivity bimodules over noncommutative tori. We explore several links between Gabor frames and noncommutative tori, and show how operator algebras can be used to give alternative proofs of theorems from time-frequency analysis.  This talk is based on my Master’s thesis written at NTNU, which reviews Franz Luef’s work on the connections between Gabor frames and modules over noncommutative tori, as well as some joint work with Franz Luef.

Tid og sted: 12. des. 2016 13:15 - 14:00, Niels Henrik Abels hus, room 1036

Rodwell Kufakunesu (University of Pretoria, South Africa) gives a lecture with the title: Pricing and hedging quanto commodity options.

Tid og sted: 12. des. 2016 12:15 - 13:00, Niels Henrik Abels hus, room 1036

Nacira Agram (University of Oslo) gives a lecture with the title: Model Uncertainty Stochastic Mean-Field Control.

Tid og sted: 8. des. 2016 11:15 - 13:00, B 738

A continuation of part I.

Tid og sted: 7. des. 2016 10:15 - 12:00, NHA, seminarrom B81

John Quigg, Arizona State University (Tempe), USA, will give a talk with title "The Pedersen rigidity problem".

University of Abstract: If \alpha is an action of a locally compact abelian group G on a C*-algebra A, Takesaki-Takai duality recovers (A,\alpha) up to Morita equivalence from the dual action of \widehat{G} on the crossed product A\rtimes_\alpha G. Given a bit more information, Landstad duality recovers (A,\alpha) up to isomorphism. In between these, by modifying a theorem of Pedersen, (A,\alpha) is recovered up to outer conjugacy from the dual action and the position of A in M(A\rtimes_\alpha G). Our search (still unsuccessful, somehow irritating) for examples showing the necessity of this latter condition has led us to formulate the "Pedersen rigidity problem". We present numerous situations where the condition is redundant, including G discrete or A stable or commutative. The most interesting of these "no-go theorems" is for locally unitary actions on continuous-trace algebras. This is joint work with Steve Kaliszewski and Tron Omland. 

Tid: 6. des. 2016 14:15

Riccardo De Bin (Department of Mathematics, University of Oslo) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.

Tid og sted: 6. des. 2016 10:15 - 12:00, B 738

Framed correspondences were invented and studied by Voevodsky in the early 2000-s, aiming at the construction of a new model for motivic stable homotopy theory. Joint with Ivan Panin we introduce and study framed motives of algebraic varieties basing on Voevodsky's framed correspondences. Framed motives allow to construct an explicit model for the suspension P1-spectrum of an algebraic variety. Framed correspondences also give a kind of motivic infinite loop space machine. They also lead to several important explicit computations such as rational motivic homotopy theory or recovering the celebrated Morel theorem that computes certain motivic homotopy groups of the motivic sphere spectrum in terms of Milnor-Witt K-theory. In these lectures we shall discuss basic facts on framed correspondences and related constructions.  

Tid og sted: 2. des. 2016 11:15 - 12:00, NHA bygget 9 etg B91

Stereolithography - A Powerful Tool to Create almost Everything

Stereolithography or "SLA" printing is a powerful and widely used 3D printing technology for creating prototypes, models, and fully functional parts for production. This additive manufacturing process works by focusing an ultraviolet (UV) laser onto a vat of liquid resin. Layer by layer formation of a polymeric network allows printing parts that are almost impossible to create with other processes.At Formlabs, a startup that originated out of the MIT Media lab in 2011, we work on all aspects of SLA printing; we develop and manufacture 3D printers, resins, and software. In this talk, I will give a detailed overview of the printer technology, the chemistry of the materials, and how to use SLA for lots of exciting applications.