## Visiting address

Niels Henrik Abels husMoltke Moes vei 35 (map)

0851 OSLO

Norway

Time and place:
Mar. 16, 2017 2:15 PM - 4:00 PM,
B638, NH Abels hus

Time and place:
Mar. 15, 2017 2:15 PM - 4:00 PM,
B 738

In the 80's Bökstedt introduced THH(A), the Topological Hochschild homology of a ring A, and a trace map from algebraic K-theory of A to THH(A). This trace map, along with the circle action on THH, have since been used extensively to make calculations of algebraic K-theory. When the ring A has an anti-involution Hesselholt and Madsen have promoted the spectrum K(A) to a genuine Z/2-spectrum whose fixed points is the K-theory of Hermitian forms over A. They also introduced Real topological Hochschild homology THR(A), which is a genuine equivariant refinement of THH, and Dotto constructed an equivariant refinement of Bökstedt's trace map. I will report on recent joint work with Dotto, Patchkoria and Reeh on models for the spectrum THR(A) and calculations of its RO(Z/2)-graded homotopy groups.

Time and place:
Mar. 15, 2017 10:15 AM - 12:00 PM,
NHA 738

Adam Sørensen (Oslo) will give a talk with title: Overlapping qubits

Abstract: I will discuss the paper "Overlapping Qubits" by Chao, Reichardt, Sutherland, and Vidick (arXiv:1701.01062 - category: Quantum Physics!). Qubits are the bits of quantum computing. In the paper the authors take the point of view that a qubit mathematically is described by a pair of anticommuting reflections on a finite dimensional Hilbert space. Two qubits are independent if their defining operators commute. The central point of the paper is that when performing observations we should not expect two qubits to be exactly independent, rather we should expect them to be almost independent, i.e. the norms of the commutators should be small. This naturally leads to questions about almost commuting matrices, which is why I care. I will attempt to explain how questions of almost commuting matrices come up, and how the physicists answer them.

Time and place:
Mar. 10, 2017 11:15 AM - 12:00 PM,
NHA 935

Large Eddy Simulation of the interaction of water waves with turbulent air flow

Time and place:
Mar. 10, 2017 11:15 AM - 12:00 PM,
Niels Henrik Abels hus, room UE32

Youssef Ouknine (Cadi Ayyad University, Marrakesh, Morocco) gives a lecture with the title: Optimal stopping with f-expectations: the irregular case.

Time and place:
Mar. 10, 2017 10:15 AM - 11:00 AM,
Niels Henrik Abels hus, room UE32

Khalifa Essebaly (Cadi Ayyad University, Marrakesh, Morocco) gives a lecture with the title: Optimal rates for parameter estimation of stationary Gaussian processes.

Time:
Mar. 7, 2017 2:15 PM

Lan Zhang (University of Illinois at Chicago, Department of Finance) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.

Time:
Feb. 28, 2017 2:15 PM

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.

Time and place:
Feb. 22, 2017 2:15 PM - 4:00 PM,
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.

Time and place:
Feb. 22, 2017 12:15 PM - 2:00 PM,
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.

Time and place:
Feb. 16, 2017 2:15 PM - 4:00 PM,
B638, NH Abels hus

Time and place:
Feb. 16, 2017 2:15 PM - 4:00 PM,
B638, NH Abels hus

Time and place:
Feb. 13, 2017 2:00 PM - 3:00 PM,
NHA 935

Time and place:
Feb. 10, 2017 1:15 PM,
Aud. 2, Vilhelm Bjerknes' hus

M.Sc. Abushet W. Simanesew ved Matematisk institutt vil forsvare sin avhandling for graden ph.d.:

**Directional characteristics and surface wave predictions in weakly nonlinear directional seas**

Time and place:
Feb. 10, 2017 10:15 AM,
Aud. 2, Vilhelm Bjerknes' hus

M.Sc. Abushet W. Simanesew ved Matematisk institutt avholder prøveforelesning over oppgitt emne: "Modeling and Simulation of Avalanches".

Time and place:
Feb. 9, 2017 3:15 PM - 5:00 PM,
NHA room 735

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

Time and place:
Feb. 9, 2017 2:15 PM - 4:00 PM,
B638, NH Abels hus

Time and place:
Feb. 9, 2017 2:15 PM - 4:00 PM,
B638, NH Abels hus

Time and place:
Feb. 6, 2017 1:15 PM - 2:00 PM,
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

Time and place:
Feb. 1, 2017 2:15 PM - 4:00 PM,
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.

Time:
Jan. 31, 2017 2:15 PM

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.

Time and place:
Jan. 26, 2017 11:00 AM -
Jan. 28, 2017 3:00 PM,
University of Oslo

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

Time and place:
Jan. 13, 2017 1:15 PM,
"Abels utsikt", 12. etasje Niels Henrik Abels hus

Siv.ing. Marie Lilleborge ved Matematisk institutt vil forsvare sin avhandling for graden ph.d.:

**Efficient Information Gathering in Bayesian Networks**

Time and place:
Jan. 13, 2017 10:15 AM,
"Abels utsikt", 12. etasje Niels Henrik Abels hus

Siv.ing. Marie Lilleborge ved Matematisk institutt avholder prøveforelesning over oppgitt emne: "Inference in Bayesian networks".