Math Calendar

Friday, May 25, 2018
14:00-16:00
HFG 610
Friday Fish
Damien Lejay - About a Kontsevich conjecture on vertex models

Vertex models are models of statistical mechanics on a lattice, in which the Boltzmann weights are associated with vertices of the lattice. Quantities associated with a system, such as the energy, may diverge when the size of the lattice is infinite. Renormalisation techniques are then used to try to overcome this difficulty. Problems occurring for models of statistical mechanics are similar in nature to divergency problems in quantum field theory. Kontsevich has suggested an approach to the renormalisation question in quantum field theory that would in particular imply the following statement, which still remains not fully precise as there is not satisfactory definition yet of what a QFT is: ‘For any QFT on R^d with invariance under the action of the group of parallel translations and dilations, translation invariant forms with values in local fiels form an algebra over the little disc operads E_d’. Today we shall describe a more precise conjecture made by Kontsevich in the case of vertex models. This work is joint with Damien Calaque.
Monday, May 28, 2018
11:00-13:00
HFG 610
Monday Fish
Ori Yudilevich - An Application of the theory of EDS to G-Structures

Following a paper by Singer & Sternberg, I will present an application of the framework of Exterior Differential Systems (and the Cartan-Kähler Theorem, in particular) to the theory of G-Structures. I will prove that, in the real-analytic category, if two G-structure have constant intrinsic torsion and the two intrinsic torsions are equal, then the G-structures are locally equivalent (=isomorphic). As a corollary, we will conclude that the so-called transitive G-structures are precisely those with constant intrinsic torsion.
15:30-16:30
HFG 420
Master thesis
Paul Visscher - Forecasting Time Series with Artificial Neural Networks

Abstract:

 

ArtificialNeural Networks (ANN) are used as universal approximators and are gettingwidely adopted in several working fields such as finance.

One ofthe problems that can be addressed using ANN is the forecasting of time series.Time series forecasting is known to be a difficult problem, often requiringexpert knowledge, and can be applied to problems including predicting stockvalue, sales forecasting, and inventory.  We explore how the sparsity thatoccurs in trained ANNs can be used to generalize the network topology to anyDirected Acyclic Graph (DAG). We show how both the Feed-forward Neural Network(FNN) and Recurrent Neural Network (RNN) topologies can be generalized in bothtraining and prediction. Finally we train these network architectures onbenchmark problems and use them to forecast time series.

Tuesday, May 29, 2018
12:00-13:00
HFG Library
Bring Your Own Lunch (BYOL)
13:15-15:00
HFG 610
Master Seminar on topological K-theory
t.b.a. - t.b.a.
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
HFG 611
Utrecht Geometry Center Seminar
Milan Lopuhaä-Zwakenberg (Nijmegen) - Counting torsion groups of abelian varieties
Abstract: Let $p$ be a prime number, and let $A$ be an abelian variety over a finite field $k$ of characteristic $p$. Let $A[p]$ be the $p$-torsion of $A$. As an abstract group this equals $(Z/pZ)^n$ for some $n$, but as a group scheme it can exhibit interesting infinitesimal structures. The goal of this talk is to answer the following question: "given the field $k$ and the integer $dim(A)$, how many isomorphism classes of $A[p]$ exist?" We will show that this question is best discussed in the context of algebraic stacks, where we can answer this question using the language of linear algebraic groups.
Thursday, May 31, 2018
15:00-17:00
HFG 610
Master Seminar on Quadratic Forms
Angelo Mekenkamp - Composition of forms
Monday, June 4, 2018
15:00-17:00
HFG 610
Master Seminar on Quadratic Forms
Lars van de Berg - Milnor K2 groups
Tuesday, June 5, 2018
13:15-15:00
HFG 610
Master Seminar on topological K-theory
t.b.a. - t.b.a.
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
HFG 611
Utrecht Geometry Center Seminar
Clément Dupont (Université de Montpellier) - Linear forms in zeta values, and mixed Tate motives
Abstract: In order to study the diophantine properties of the values of the Riemann zeta functions at integers, one often needs to produce integrals that evaluate to linear forms in zeta values with rational coefficients. This is in particular the case in Beukers’s proof of Apéry’s theorem on zeta(3) or in Ball and Rivoal’s proof that infinitely many odd zeta values are irrational. In this talk, we will follow a program initiated by Brown which aims at explaining and producing such linear forms by means of algebraic geometry. More precisely, we will study a family of mixed Tate motives which underlies a family of integrals generalizing Ball and Rivoal's. In particular, the explicit computation of their period matrices gives integral formulas for the coefficients of the linear forms.
Thursday, June 7, 2018
16:00-17:00
HFG 611
Complex Systems Seminar
Stefan Kroemer (UTIA Prague) - TBA
Monday, June 11, 2018
15:00-17:00
HFG 610
Master Seminar on Quadratic Forms
Marc Houben - Springer's theorem and the Cassels-Pfister theorem
Tuesday, June 12, 2018
13:15-15:00
HFG 610
Master Seminar on topological K-theory
t.b.a. - t.b.a.
14:30-16:00
Academiegebouw
PhD defense
Joost Nuiten - Lie algebroids in derived differential topology
15:30-16:00
HFG Library
Institute Tea
Thursday, June 14, 2018
15:30-16:30
Ruppert ROOD
The Utrecht Mathematical Colloquium / The 4th Daniel Kan Memorial Lectures I
Eric Friedlander (USC) - Modular representation theory
Friday, June 15, 2018
11:00-12:00
KBG Pangea
The 4th Daniel Kan Memorial Lectures II
Eric Friedlander (USC) - Cohomology of finite group schemes
14:00-15:00
KBG Pangea
The 4th Daniel Kan Memorial Lectures III
Eric Friedlander (USC) - Results for Drinfeld doubles of finite group schemes
Monday, June 18, 2018
15:00-17:00
HFG 610
Master Seminar on Quadratic Forms
Bart van Hoek - Alternative algebra’s, quadratic algebras and octonions
Tuesday, June 19, 2018
12:00-13:00
HFG Library
Bring Your Own Lunch (BYOL)
13:15-15:00
HFG 610
Master Seminar on topological K-theory
t.b.a. - t.b.a.
15:30-16:00
HFG Library
Institute Tea
Thursday, June 21, 2018
16:00-17:00
Extra Number Theory Talk
Mikhail Borovoi (Tel Aviv University) - Cayley groups, MIN 2.06
I will start the talk from the classical "Cayley transform" for the special orthogonal group SO(n) defined by Arthur Cayley in 1846. A connected linear algebraic group G over C is called a *Cayley group* if it admits a *Cayley map*, that is, a G-equivariant birational isomorphism between the group variety G and its Lie algebra Lie(G). For example, SO(n) is a Cayley group; A linear algebraic group G is called *stably Cayley* if G x S is Cayley for some torus S. I will consider semisimple algebraic groups, in particular, simple algebraic groups. I will describe classification of Cayley simple groups and of stably Cayley semisimple groups. (Based on joint works with Boris Kunyavskii and others.)
Monday, June 25, 2018
13:00-15:00
HFG 610
Master Seminar on Quadratic Forms
Jeroen Huijben - The dimension of a real division algebra is a power of 2
15:00-17:00
HFG 610
Master Seminar on Quadratic Forms
Berend Ringeling - The dimension of a real division algebra is 1/2/4/8
Tuesday, June 26, 2018
13:15-15:00
HFG 610
Master Seminar on topological K-theory
t.b.a. - t.b.a.
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
HFG 611
Utrecht Geometry Center Seminar
Diogo Oliveira e Silva (University of Birmingham, UK) - t.b.a.
Tuesday, July 3, 2018
13:15-15:00
HFG 610
Master Seminar on topological K-theory
t.b.a. - t.b.a.
15:30-16:00
HFG Library
Institute Tea
Tuesday, July 10, 2018
13:15-15:00
HFG 610
Master Seminar on topological K-theory
t.b.a. - t.b.a.
15:30-16:00
HFG Library
Institute Tea
Tuesday, September 11, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, September 18, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, September 25, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, October 2, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, October 9, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, October 16, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, October 23, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, October 30, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, November 6, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, November 13, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611
Tuesday, November 20, 2018
15:30-16:00
HFG Library
Institute Tea
16:00-17:00
Utrecht Geometry Center Seminar
t.b.a. - t.b.a., HFG 611