## Visiting address

Ullevål StadionSognsveien 77B

0855 OSLO

Norway

Time and place:
May 9, 2018 11:15 AM - 12:00 PM,
Seminar room "End of the Line"

Time and place:
May 4, 2018 12:45 PM - 1:45 PM,
Gates of Eden, Sognsv. 77B

Time and place:
May 3, 2018 1:00 PM - 2:00 PM,
Hurricane, Ullevål

Kurusch Ebrahimi-Fard (NTNU) will give a talk with title: Moment-cumulant relations in noncommutative probability and shuffle-exponentials

Abstract: In this talk we consider monotone, free, and boolean moment-cumulant relations from the shuffle algebra viewpoint. Cumulants are described as infinitesimal characters over a particular combinatorial Hopf algebra, which is neither commutative nor cocommutative. As a result the moment-cumulant relations can be encoded in terms of shuffle and half-shuffle exponentials. These shuffle exponentials and the corresponding logarithms permit to express monotone, free, and boolean cumulants in terms of each other using the pre-Lie Magnus expansion. If time permits we will revisit additive convolution in monotone, free and boolean probability and related aspects. Based on joint work with F. Patras (CNRS).

Time and place:
May 2, 2018 2:15 PM - 4:00 PM,
Gates of Eden, Sognsveien 77 B

In this second talk I will prove the local slice theorem and give examples of applications, discuss compactness properties of instanton moduli spaces, and explain the definition and some properties of instanton homology.

Time and place:
May 2, 2018 11:20 AM - 12:00 PM,
Desolation Row Sognsveien 77 B

In their book "Riemann-Roch Algebra", Fulton and Lang give an account of Chern classes in lambda-rings and a general version of Grothendieck's Riemann-Roch theorem. Their definition of Chern classes is based on the additive formal group law. In work on connective K-theory, Greenlees and I have given an account of Chern classes in lambda-rings based on the multiplicative formal group law. This account has an evident generalization to any formal group law. The course will be an attempt to carry out Fulton and Lang's program in this more general setting. Hoped for applications include generalizations of results relating rational lambda-modules to twisted Dirichlet characters. ---

Time and place:
May 2, 2018 10:15 AM - 11:05 AM,
Desolation Row Sognsveien 77 B

Time and place:
May 2, 2018 9:30 AM -
May 4, 2018 4:30 PM,
Auditorium 2 of the science library building Vilhelm Bjerknes' hus

The third Scandinavian Gathering Around Remarkable Discrete Mathematics

Time and place:
Apr. 25, 2018 1:00 PM - 2:00 PM,
Gates of Eden, Sognsv. 77B

Associate Professor Erik Adli from the Department of Physics at UiO will give a Colloquium Talk on

** Particle Accelerators**

Time and place:
Apr. 20, 2018 1:15 PM,
Ullevål Stadion: Gates of Eden

M.Sc. Torkel Andreas Haufmann ved Matematisk institutt vil forsvare sin avhandling for graden ph.d.:

**Some topics in combinatorial matrix theory and on the k-regular induced subgraph problem**

Time and place:
Apr. 11, 2018 2:15 PM - 4:00 PM,
Desolation Row, Sognsveien 77 B

Waldhausen's algebraic K-theory of spaces is an extension of algebraic K-theory from rings to spaces (or ring spectra) which also encodes important geometric information about manifolds. Bivariant A-theory is a bivariant extension of algebraic K-theory from spaces to fibrations of spaces. In this talk, I will first recall the definition and basic properties of bivariant A-theory and the A-theory Euler characteristic of Dwyer-Weiss-Williams. I will then introduce a bivariant version of the cobordism category and explain how this may be regarded as a universal space for the definition of additive characteristic classes of smooth bundles. Lastly, I will introduce a bivariant extension of the Dwyer-Weiss-Williams characteristic and discuss the Dwyer-Weiss-Williams smooth index theorem in this context. Time permitting, I will also discuss some ongoing related work on the cobordism category of h-cobordisms. This is joint work with W. Steimle.

Time and place:
Apr. 11, 2018 11:15 AM - 12:00 PM,
Seminar room "End of the Line"

Time and place:
Apr. 9, 2018 1:15 PM,
Ullevål Stadion: Gates of Eden

M.Sc. Rune Vegard Skullerud Fjellbo ved Matematisk institutt vil forsvare sin avhandling for graden ph.d.:

**Non-singular simplicial sets**

Time and place:
Apr. 9, 2018 10:15 AM,
Ullevål Stadion: Gates of Eden

M.Sc. Torkel Andreas Haufmann ved Matematisk institutt avholder prøveforelesning over oppgitt emne: "Nonnegative factorization rank of a nonnegative matrix".

Time and place:
Apr. 9, 2018 10:15 AM,
Ullevål Stadion: Gates of Eden

M.Sc. Rune Vegard Skullerud Fjellbo ved Matematisk institutt avholder prøveforelesning over oppgitt emne: "The s-cobordism theorem".

Time and place:
Apr. 3, 2018 10:30 AM - 12:00 PM,
Gates of Eden

On Tuesday the 3rd of April there will be a presentation on the modern problems facing research data and its use. It is highly recommended that all employees at the Department of Mathematics attend.

The presentation will be held in English.

Time:
Mar. 26, 2018 10:15 AM -
Mar. 30, 2018 12:00 PM

Paul Arne Østvær will speak at the conference Motives in Tokyo, which will be held in honor of Shuji Saito's 60th birthday.

Time and place:
Mar. 22, 2018 12:45 PM - 1:45 PM,
Gates of Eden Sognsveien 77 B

The speedskating 1000-m is a Formula One event, for the Olympics and the annual World Sprint Championships. The skaters are running in pairs, with one starting in inner lane and the other in outer lane, and then exchanging lanes on the backstretch. With speeds up to 60 km/h, there will in particular be technical challenges when negogiating the curves. Once upon a time I managed to change the Olympics, by pinpointing the statistically significant non-zero difference between last inner and last outer lane for the 500-m; the practical solution is to have the skaters running the 500-m twice, with one start in inner and one in outer. I have now properly examined the 1000-m, and found that there is a similar and in fact more dramatic Olympic Unfairness Parameter associated with that event.

Coffee and cakes from 12.00 in the lunch room.

Time and place:
Mar. 21, 2018 2:15 PM - 4:00 PM,
Desolation Row, Sognsveien 77 B

I will review Witt vectors, KÃ€hler forms and logarithmic rings, and outline how they merge in the logarithmic de Rham-Witt complex. This structure gives an algebraic underpinning for the Hesselholt-Madsen (2003) calculation of logarithmic topological cyclic homology of many discrete valuation rings.

Time and place:
Mar. 20, 2018 10:15 AM - 12:00 PM,
End of the Line, Sognsveien 77 B

This talk is supposed to be an Introductionary talk to the preprint arXiv:1409.4372v4 (joint work with G.Garkusha). More specifically, using the theory of framed correspondences developed by Voevodsky, the authors introduce and study framed motives of algebraic varieties. This study gives rise to a construction of the big frame motive functor. It is shown that this functor converts the classical Morel--Voevodsky motivic stable homotopy theory into an equivalent local theory of framed bispectra, and thus producing a new approach to stable motivic homotopy theory. As a topological application, it is proved that for the simplicial set Fr(Delta^\bullet_C, S^{^1}) has the homotopy type of the space \Omega^{\infty} Sigma^{\infty} (S^{^1}). Here C is the field complex numbers.

Time and place:
Mar. 20, 2018 10:15 AM - 12:00 PM,
End of the line

This talk is supposed to be an Introductionary talk to the preprint arXiv:1409.4372v4 (joint work with G.Garkusha). More specifically, using the theory of framed correspondences developed by Voevodsky, the authors introduce and study framed motives of algebraic varieties. This study gives rise to a construction of the big frame motive functor. It is shown that this functor converts the classical Morel--Voevodsky motivic stable homotopy theory into an equivalent local theory of framed bispectra, and thus producing a new approach to stable motivic homotopy theory. As a topological application, it is proved that for the simplicial set $Fr(Delta^\bullet_C, S^1)$ has the homotopy type of the space $\Omega^{\infty} Sigma^{\infty} (S^1)$. Here C is the field complex numbers.

Time and place:
Mar. 14, 2018 10:15 AM - 12:00 PM,
Desolation row

Time and place:
Mar. 13, 2018 11:15 AM - 12:00 PM,
End of the line

In this talk, we will present a relation between the classical Chow group of relative 0-cycles on a regular scheme *X*, projective and flat over an excellent Henselian discrete valuation ring *A* with perfect residue field *k*, and the so-called cohomological Chow group of zero cycles of the special fiber. If *k* algebraically closed and with finite coefficients (prime to the residue characteristic) these groups turn out to be isomorphic. This generalizes a previous argument due to Esnault-Kerz-Wittenberg to the case of regular models with arbitrary reduction. From this, one can re-prove in case of bad reduction that the étale cycle class map for relative 0-cycles with finite coefficients on *X* is an isomorphism, a result due to Saito and Sato in the case of semi-stable reduction. This is a joint work with Amalendu Krishna.

Time and place:
Mar. 13, 2018 10:15 AM - 11:00 AM,
End of the line

Grothendieck invented the category of numerical motives. From this, the abelian category of pure motives can be obtained assuming his conjectures. This category serves as a universal cohomology theory for schemes smooth and projective over a field. It is expected that there is an abelian category of mixed motives, which contains the abelian category of pure motives as a full subcategory and serves as a universal cohomology theory for schemes smooth but not necessarily projective over a field. I will explain how mixed motives looks assuming several conjectures, and I will give some unconditional examples including 2-motives.

Time and place:
Mar. 8, 2018 10:15 AM - 2:00 PM,
Desolation Row Sognsveien 77 B

I discuss how Bökstedt and Madsen (1994/1995) calculate mod p homotopy for THH(Z) and the fixed-point spectra THH(Z)^{C_{p^n}}, together with the R- and F-operators. This leads to a calculation for TC(Z; p) and K(Z_p), confirming the Lichtenbaum-Quillen conjecture in this case.

Time and place:
Mar. 7, 2018 2:15 PM - 4:00 PM,
Desolation Row, Sognsveien 77 B

I will review Bökstedt, Hesselholt and Madsen's calculations of the topological cyclic homology of prime fields and the integers, again taking into account simplifications made in later papers. (If necessary, I will continue on Thursday.)