## Visiting address

Ullevål StadionSognsveien 77B

0855 OSLO

Norway

Time and place:
Nov. 8, 2017 3:00 PM - 4:00 PM,
Hurricane, Sognsveien 77 b

I will discuss the algebra structure of the E_2-term of the mod 2 Adams spectral sequence for tmf, given by the cohomology Ext_{A(2)}(F_2, F_2) of A(2). We (Bruner & Rognes) use Groebner bases to verify the presentation given by Iwai and Shimada, with 13 generators and 54 relations. Thereafter I will discuss the relationship between differentials and Steenrod operations in the Adams spectral sequence for E_\infty ring spectra.

Time and place:
Nov. 8, 2017 1:15 PM,
Ullevål Stadion: Gates of Eden

M.Sc. Fredrik Meyer ved Matematisk institutt vil forsvare sin avhandling for graden ph.d.:

**Join of hexagons and Calabi–Yau threefolds**

Time and place:
Nov. 8, 2017 12:00 PM -
Nov. 9, 2017 1:00 PM,
Seminar room: "Desolation Row" (3rd floor) on November 8 and "Gates of Eden" (2nd floor) on November 9, Matematisk Institutt, Sognsveien 77B, Ullevål Stadion

Welcome to the second FINEWSTOCH Networkshop. The workshop will bring together leading researchers in stochastics and probability theory to discuss recent developments with a particular focus on finance, insurance, energy and weather.

Time and place:
Nov. 8, 2017 10:15 AM,
Gates of Eden, Ullevål stadion

M.Sc. Fredrik Meyer ved Matematisk institutt avholder prøveforelesning over oppgitt emne: "Prym varieties: basic constructions and central results".

Time and place:
Nov. 8, 2017 10:15 AM,
Gates of Eden, Ullevål stadion

M.Sc. Espen Stokkereit ved Matematisk institutt avholder prøveforelesning over oppgitt emne: "Rough path theory".

Time and place:
Nov. 6, 2017 12:45 PM - 1:45 PM,
End of Line, Ullevål

Pawel Kasprzak (Warzaw) will give a talk with title " Quantum actions on discrete quantum spaces"

Abstract:

To any action of a compact quantum group on a von Neumann algebra which is a direct sum of factors we associate an equivalence relation corresponding to the partition of a space into orbits of the action. We show that in case all factors are finite-dimensional (i.e. when the action is on a discrete quantum space) the relation has finite orbits. We then apply this

i) to generalize the classical theory of Clifford, concerning the restrictions of representations to normal subgroups, to the framework of quantum subgroups of discrete quantum groups, itself extending the context of closed normal quantum subgroups of compact quantum groups; ii) to the context of idempotent states showing that the algebra of invariant elements is finite dimensional if and only if the corresponding state is normal. Joint work with K. De Commer, A. Skalski and P. Sołtan.

Time and place:
Nov. 2, 2017 2:30 PM - 3:30 PM,
Gates of Eden, Sognsv. 77 B

Professor Emeritus **Erling Størmer** will turn 80 on November 2, and he will use this occasion to give a Colloquium Talk with tittle:

POSITIVE LINEAR MAPS ON MATRIX ALGEBRAS

*Abstract: The first part of the talk will be an introduction to the theory of positive linear maps between matrix algebras, plus a few words on the operator algebra case. For the last 20 years, physicists working in quantum information theory have been active in the subject and I’ll devote the last half of the talk to a negative solution to a conjecture they had. *

Time and place:
Nov. 2, 2017 10:15 AM - 11:00 AM,
Gates of Eden

**When and how surface structure determines the dynamics of partial wetting**

Time and place:
Nov. 1, 2017 2:15 PM - 4:00 PM,
Desolation Row, Sognsveien 77 B

I will discuss machine computations in a finite range, using Bruner's ext-program, of Ext over A, the mod 2 Steenrod algebra, and over A(2), the subalgebra of A generated by Sq^{^1}, Sq^{^2} and Sq^{^4}. These are the E_2-terms of the mod 2 Adams spectral sequences for S and tmf, respectively.

Time and place:
Oct. 30, 2017 3:15 PM - 4:00 PM,
Hurricane

**Sedimentation-diffusion equilibrium of Quincke rollers**

Time and place:
Oct. 26, 2017 2:15 PM - 4:00 PM,
Ullevål

Time and place:
Oct. 23, 2017 12:45 PM - 1:45 PM,
Gates of Eden

Erik Bedos (UiO) will give a talk with title "On Exel-Pardo algebras as Cuntz-Pimsner algebras"

Abstract:

In a joint work with S. Kaliszweski and J. Quigg (https://arxiv.org/pdf/1512.07302.pdf, to appear in JOT), we consider a continuous action of a locally compact group G on a topological graph E, equipped with a G-valued continuous cocycle, and show how to construct a C*-correspondence from these data, giving rise to a Toeplitz algebra and a Cuntz-Pimsner algebra. In the talk we will sketch this construction, but restrict ourselves to the discrete case. We will also describe these algebras in terms of generators and relations when E is row-finite. As a corollary we get that the associated Cuntz-Pimsner algebra coincides with the C*-algebra recently introduced by Exel and Pardo when E is finite and sourceless.

Time and place:
Oct. 20, 2017 11:15 AM - 12:00 PM,
Hurricane

Reyna Ramirez

Time and place:
Oct. 19, 2017 2:15 PM - 4:00 PM,
Ullevål

Time and place:
Oct. 16, 2017 12:45 PM - 1:45 PM,
Gates of Eden, Ullevål

Nicolai Stammeier (Oslo) will give a talk with title: The inner structure of boundary quotients of right LCM semigroups

Abstract: In joint work with Roberto Conti, Stefano Rossi, and Valeriano Aiello, we use semidirect products built from algebraic dynamical systems to model right LCM semigroups to study various structural aspects in connection with a selection of distinguished subalgebras of the associated boundary quotients. Our two guiding examples are integral dynamics as considered in work of Barlak - Omland - Stammeier, and exact injective group endomorphisms of discrete abelian groups with finite cokernel as studied by Cuntz and Vershik.

Time and place:
Oct. 12, 2017 2:15 PM - 4:00 PM,
Ullevål

Time and place:
Oct. 11, 2017 1:15 PM - 2:00 PM,
Seminar room: "Hurricane", Matematisk Institutt, Ullevål stadion (Sognsveien 77 B, 2nd floor)

Eric Schaanning (Norges Bank) gives a lecture with the title: Interbank contagion and systemic risk: How robust are estimates?

Time and place:
Sep. 27, 2017 2:15 PM - 4:00 PM,
B638, NH Abels hus

Time and place:
Sep. 27, 2017 1:15 PM,
Eilert Sundts hus, A-blokka: Auditorium 1

M.Sc. Endre Joachim Mossige ved Matematisk institutt vil forsvare sin avhandling for graden ph.d.:

**Continuous Hydrodynamic Separation and Concentration of Particles according to Size by use of the Trilobite Technology**

Time and place:
Sep. 27, 2017 10:15 AM,
Vilhelm Bjerknes' hus: Auditorium 1

M.Sc. Endre Joachim Mossige ved Matematisk institutt avholder prøveforelesning over oppgitt emne: "The physics behind a perfectly boiled egg".

Time and place:
Sep. 21, 2017 2:15 PM - 4:00 PM,
B638, NH Abels hus

Time and place:
Sep. 19, 2017 12:45 PM - 1:45 PM,
Gates of Eden

Adam Sørensen (UiO) will give a talk with title: C*-stable groups.

Abstract: In this talk we will look at when group C*-algebra have stable relations, which loosely speaking means that any almost representation of the group in a C*-algebra will be close to an exact representation. A particularly interesting case is if we assume the C*-algebra is finite dimensional. I will mostly discuss a collection of examples. The talk is based on ongoing joint work with Søren Eilers and Tatiana Shulman.

Time and place:
Sep. 7, 2017 10:15 AM - 12:00 PM,
Ole Johan Dahls hus

The seminar takes place in the meeting room, floor 9 of Ole Johan Dahls hus.

The room has been reserved Thursdays 10.15 - 12.00 from August 31 to November 30.

The program is subject to changes.