## Visiting address

Ullevål StadionSognsveien 77B

0855 OSLO

Norway

Time and place:
Mar. 4, 2015 2:15 PM - 4:00 PM,
NHA B735

Bartosz K. Kwaśniewski (University of Southern Denmark, Odense) will talk on: Topological aperiodicity for product systems of C*-correspondences

Abstract:We introduce a semigroup of multivalued maps dual to a product system of $C^*$-correspondences over an Ore semigroup. Under a certain aperiodicity condition on the dual semigroup we obtain a uniqueness theorem and a simplicity criterion for the associated Cuntz-Pimsner algebra. These results generalize similar statements for crossed products by groups (R. J. Archbold, J. S. Spielberg) and Exel’s crossed products (R. Exel, A. Vershik). They also give interesting conditions for topological higher rank graphs, and apply to the new Cuntz $C^*$-algebra $\mathcal{Q}_\mathbb{N}$ arising from the `$ax+b$'-semigroup over natural numbers. (Based on joint work with Wojciech Szymański.)

Time and place:
Feb. 26, 2015 2:15 PM - 4:00 PM,
B62, NH Abels hus

Geir Ellingsrud, UiO, gives the Seminar in Algebra and Algebraic Geometry:

Modular curves I

Time and place:
Feb. 25, 2015 2:15 PM - 4:00 PM,
NHA B71

Adam P.W. Sørensen will talk on Nuclear dimension of UCT Kirchberg algebras

Abstract: Nuclear Dimension is a regularity property for C*-algebras that is based on the type of properties currently being taught in Topics in Operator Algebras. We will go over the definition and motivation and discuss known results.

Time:
Feb. 24, 2015 2:15 PM

Kasper Christensen ( Nofima, Ås and Aarhus university ) gives a seminar in room 107, 1st floor N.H. Abels House at 14:15 February 24th: Mining for new product ideas.

Time and place:
Feb. 18, 2015 2:15 PM - 3:15 PM,
NHA B735

Time and place:
Feb. 12, 2015 2:15 PM - 4:00 PM,
B62, NH Abels hus

Atanas Iliev, Seoul National University, gives the Seminar in Algebra and Algebraic Geometry:

Fano manifolds - old and new

Time and place:
Feb. 11, 2015 2:15 PM - 4:00 PM,
NHA B735

Makoto Yamashita, Ochanomizu University, will give a talk with title: Drinfeld center and representation theory for monoidal categories

Abstract: Motivated by the recently found relation between central completely positive multipliers and the spherical unitary representations of the Drinfeld double for discrete quantum groups, we construct and analyze the representations of fusion algebra of rigid C*-tensor category from the unitary half-braidings. Through the correspondence of Drinfeld center and the generalized Longo-Rehren construction in subfactor theory, these representations are also related to Popa’s theory of correspondences and subfactors. This talk is based on joint work with Sergey Neshveyev.

Time and place:
Feb. 10, 2015 2:15 PM,
Room 107, 1st floor N.H. Abels House

Håvard Rue ( Dept. of math., NTNU) gives a seminar in room 107, 1st floor N.H. Abels House at 14:15 February 10th: Penalising model component complexity: A principled practical approach to constructing priors

Time and place:
Feb. 5, 2015 1:00 PM - 3:00 PM,
Undervisningsrom 126 Niels Henrik Abels hus

Her er innledning

Time and place:
Feb. 3, 2015 2:15 PM,
rom 107, N.H. Abels hus

Helge Brunborg (Statistisk sentralbyrå) holder et seminar i rom 107, 1. etasje N.H. Abels Hus kl. 14:15 tirsdag 3. februar: Hva skjer med verdens befolkningsutvikling?

Time and place:
Jan. 29, 2015 2:15 PM -
Jan. 29, 2014 4:00 PM,
B62, NH Abels hus

Helge Maakestad gives the Seminar in Algebra and Algebraic Geometry:

Generalized enveloping algebras, connections and characteristic classes

Time and place:
Jan. 22, 2015 2:15 PM -
Jan. 22, 2014 4:00 PM,
B62, NH Abels hus

Jan O. Kleppe, HiOA, gives the Seminar in Algebra and Algebraic Geometry:

On the Hilbert scheme of space curves

Time and place:
Jan. 8, 2015 2:15 PM -
Jan. 8, 2014 4:00 PM,
B62, NH Abels hus

Geir Ellingsrud, UiO, gives the Seminar in Algebra and Algebraic Geometry:

Abelian varieties XV: Abelian varieties are quotients of Jacobian varieties

Time and place:
Dec. 18, 2014 2:15 PM - 4:00 PM,
B62, NH Abels hus

John Christian Ottem, Cambridge University, gives the Seminar in Algebra and Algebraic Geometry:

Abelian varieties XIV: Hodge-formodningen for abelske varieteter.

Time and place:
Dec. 18, 2014 12:15 PM - 2:00 PM,
B62, NH Abels hus

Arne B. Sletsjøe, UiO, gives the Seminar in Algebra and Algebraic Geometry:

Projektive grenser av spline systemer

Time and place:
Dec. 11, 2014 2:15 PM - 4:00 PM,
B62, NH Abels hus

Arne B. Sletsjøe, UiO, gives the Seminar in Algebra and Algebraic Geometry:

Abelian varieties XIII

Time and place:
Dec. 11, 2014 9:15 AM - 10:00 AM,
B1036, 10th floor, NHA

AFEM in 3-D and beyond

Time and place:
Dec. 8, 2014 12:00 PM -
Dec. 11, 2014 9:00 AM,
Lysebu (Oslo)

Supported by the Foundation for Danish-Norwegian cooperation.

Time and place:
Dec. 4, 2014 2:15 PM - 4:00 PM,
NHA B637

Christian Voigt (Glasgow) will give a talk with title: The structure of quantum permutation groups

Abstract: Quantum permutation groups, introduced by Wang, are a quantum analogue of permutation groups. These quantum groups have a surprisingly rich structure, and they appear naturally in a variety of contexts, including combinatorics, operator algebras, and free probability. In this talk I will give an introduction to these quantum groups, and review some results on their structure. I will then present a computation of the K-groups of the C*-algebras associated with quantum permutation groups, relying on methods from the Baum-Connes conjecture.

Time and place:
Dec. 4, 2014 9:15 AM - 10:00 AM,
B1036, 10th floor, NHA

Adaptive finite elements: practice and implementation

Time and place:
Dec. 3, 2014 2:00 PM - 4:00 PM,
NHA B71

Alfons van Daele, University of Leuven (Belgium), will give a talk with title: Separability idempotents and quantum groupoids

Time and place:
Dec. 2, 2014 3:15 PM,
room 107, 1st floor N.H. Abels House

Andrea Riebler ( Dept. of math., NTNU) gives a seminar in room 107, 1st floor N.H. Abels House at 15:15 December 2nd: Projecting the future burden of cancer: Bayesian APC analysis made simple.

Time and place:
Dec. 2, 2014 1:00 PM - 3:15 PM,
room 3315 Kristine Bonnevie’s house (Biology)

Time and place:
Dec. 1, 2014 10:15 AM - 12:00 PM,
B 62 NHA

Modular forms are certain complex-analytic functions on the upper-half plane. They can also be interpreted as giving linear-algebraic invariants of elliptic curves, perhaps equipped with some extra structure, and in this way they reveal their algebraic-geometric nature. One of the most fundamental modular forms is the Dedekind eta function. However, it seems that only recently has it been pinned down precisely what extra structure on an elliptic curve is needed to define eta. Namely, Deligne was able to express this extra structure in terms of the 2- and 3-power torsion of the elliptic curve. Deligne's proof, apparently, is computational. In this talk I'll describe a conjectural reinterpretation of Deligne's result, together with some supporting results and a hint at a possible conceptual proof. The reinterpretation is homotopy theoretic, the key being to think of an elliptic curve as giving a class in framed cobordism. This directly connects the number "24" which often appears in the study of eta to the 3rd stable stem in topology.