Tidligere gjesteforelesninger og seminarer - Side 60

Friday seminar by Charles Krebs

Kathleen M. Jennings, Fafo Institute for Labour and Social Research

Adam Sørensen (UiO) will give a talk with title: Almost commuting matrices

Abstract: Two matrices A,B are said to almost commute if AB is close to BA (in a suitable norm). A question of Halmos, answered by Lin, asks if two almost commuting self-adjoint matrices are always close to two exactly commuting self-adjoint matrices. We will survey what is known about this and similar questions, and report on recent work with Loring concerning how the questions change if we look at real rather than complex matrices.

Kristan Ranestad (Dept. of Math, UiO) gives a seminar in room 107, 1st floor N.H. Abels House at 14:15 Tuesday October 14th. Algebra og statistics: Phylogenetic models from an algebraic geometric viewpoint

Jeg avslutter reduksjonen av Segalformodningen til et algebraisk spørsmål om en Ext-ekvivalens, og vil se i mer detalj på hvordan Pontryagin--Thom-konstruksjonen brukes til å bevise Wirthmüller- og Adams transfer-ekvivalensene i stabil ekvivariant homotopiteori. 

Philip Bull,Postdoctoral Fellow , ITA

Mattis B. Wigestrand: Optogenetics - Manipulating animal behavior with light

Årets Nobelpris i fysikk annonseres 7. oktober. Vi ser sendingen sammen.

Friday seminar by Horacio Schneider

Friday seminar by Lars Werdelin

-A new window on our Space environment: The polarization of the auroral emissions. A French – Norwegian discovery.

Victor Haughton, Professor of Radiology at the University of Wisconsin

and Adjunct Research Scientist at Simula Research Laboratory

Ørnulf Borgan (Department of Mathematics,UiO) gives a seminar

in room 107, 1st floor N.H. Abels House at 14:15 Tuesday September 23rd:

Using cumulative sums of martingale residuals for model checking in nested case-control studies  

Jeg vil vise hvordan Segalformodningen kan omformuleres, ved hjelp av Tatekonstruksjonen, norm-restriksjonssekvensene, Warwick dualitet og Adams' transferekvivalens, til en form som lettere lar seg bevise v.h.a. den algebraiske Singerkonstruksjonen. Dette er det andre i en serie foredrag som sikter mot å gi et bevis for en versjon av Segalformodningen i motivisk homotopiteori. 

Friday seminar by Andrea Waeschenbach from Natural History Museum, London, UK

Ole A. Andreassen, Jebsen Senter for Psykoseforskning, Klinikk for psykisk helse og avhengighet, Oslo universitetssykehus & Institutt for klinisk medisin

Abstract: We show that the discrete duals of the so called free orthogonal quantum groups have the completely contractive approximation property, analogous to the free groups. The proof relies on the structure of representation categories of these quantum groups, on the C*-algebraic structure of SUq(2), and on the free product techniques of Ricard and Xu. This talk is based on joint work with Kenny De Commer and Amaury Freslon.

Motivert av Atiyah og Segals kompletteringsteorem for ekvivariant topologisk K-teori formulerte Graeme Segal en tilsvarende formodning om ekvivariant stabil kohomotopi. Jeg vil minne om hva teoremet og formodningen sier, og vise hvordan Segalformodningen kan omformuleres, ved hjelp av norm-restriksjonssekvensene, til en form som lettere lar seg bevise v.h.a. den algebraiske Singerkonstruksjonen. Tanken er at dette skal være det første av en serie foredrag som sikter mot å gi et bevis for en versjon av Segalformodningen i motivisk homotopiteori. Dette var temaet for Thomas Gregersens PhD-avhandling fra 2012.

Prof. Sabino Matarrese, Dipartimento di Fisica e Astronomia "Galileo Galilei" Universita' degli Studi di Padova, Italy

I forbindelse med Kavlipris-uken arrangerer Det Norske Videnskaps-Akademi et åpent symposium i astrofysikk den 11. september.

Abstract: Independence has been introduced as a regularity property for pairs of commuting injective group endomorphisms of a discrete abelian group with finite cokernel by Joachim Cuntz and Anatoly Vershik. We discuss various characterisations of this regularity property and show how the statements need to be adjusted when removing the restrictions that the group has to be abelian and that the cokernels have to be finite. Somewhat surprisingly, this leads to the concept of *-commutativity. This property is defined for pairs of commuting self-maps of an arbitrary set. As an examples of *-commutativity, we explain a construction related to the Ledrappier shift and indicate how one obtains examples for independent group endomorphisms from this construction. If time permits, we will point out instances where the two notions have been readily used to obtain C*-algebraic results. Roughly speaking, both notions are designed to give rise to pairs of doubly commuting isometries, which significantly simplifies the analysis of the constructed C*-algebras. This is particularly useful when one tries to generalise results from the case of a single transformation to an action generated by finitely many transformations.

Molly Maleckar, Director, Simula School of Research and Innovation, Simula Research Laboratory