Thursday, April 4, 2024
10:00-11:00
KBG 224
AG Seminar talk
Sara Mehidi -
Abstract: tbd
16:00-17:00
HFG 611
Applied Math Seminar
Arkadi Predtetchinski (Maastricht) Zero-one Laws for a Control Problem with Random Action Sets

In many control problems there is only limited information about the actions that will be available at future stages. We introduce a framework where the Controller sequentially chooses actions $a_{0}, a_{1}, \ldots$, one at a time. Her goal is maximize the probability that the infinite sequence $(a_{0}, a_{1}, \ldots)$ is an element of a given subset $G$ of $\N^\N$. The set $G$ is assumed to be a Borel tail set. The Controller's choices are restricted: having taken a sequence $h_{t} = (a_{0}, \ldots, a_{t-1})$ of actions prior to stage $t \in \N$, she must choose an action $a_{t}$ at stage $t$ from a non-empty, finite subset $A(h_{t})$ of $\N$. The set $A(h_{t})$ is chosen from a distribution $p_{t}$, independently over all $t \in \N$ and all $h_{t} \in \N^{t}$. We consider several information structures defined by how far ahead into the future the Controller knows what actions will be available.

In the special case where all the action sets are singletons (and thus the Controller is a dummy), Kolmogorov’s 0-1 law says that the probability for the goal to be reached is 0 or 1. We construct a number of counterexamples to show that in general the value of the control problem can be strictly between 0 and 1, and derive several sufficient conditions for the 0-1 ``law" to hold.

JOINT WORK WITH: J\'{a}nos Flesch, William Sudderth, Xavier Venel

Friday, April 5, 2024
11:00-16:00
Mark Kac seminar in mathematical physics and probability
Giulia Sebastiani and Adrien Schertzer (U Frankfurt) and Vittoria Silvestri (U Rome)
Talk 1: 11-12.45

 A CRASH COURSE ON MEAN FIELD MODELS: DERRIDA’S GREM AND APPLICATIONS

Part 5 - On the GREM Approximation of TAP Free Energies. By Giulia Sebastiani.
The free energy of TAP-solutions for the SK-model of mean field spin glasses can be expressed as a nonlinear functional of local terms: 
we exploit this feature in order to contrive abstract GREM-like models which we then solve by a classical large deviations treatment. 
This allows to identify the origin of the physically unsettling quadratic (in the inverse of temperature) correction to the Parisi free energy 
for the SK-model, and formalizes thetrue cavity dynamics which acts on TAP-space, i.e. on the space of TAP-solutions. 
Joint works with Nicola Kistler, and Marius A. Schmidt. 

Part 6 - From log-correlated models to (un)directed polymers in the mean field limit. By Adrien Schertzer. 
As seen in the previous lectures, Derrida's Random Energy Models have played a key role in the understanding of certain issues in spin glasses. 
The mathematical analysis of these models -  in particular the multi-scale refinement of the second moment method as devised by Kistler, 
is also particularly efficient to analyse the so-called log-correlated class; the latter consists of Gaussian fields with - as the name suggests, 
logarithmically decaying correlations. I will introduce/recall some models falling into this class, and the main steps in their analysis 
through the paradigmatic Branching Brownian motion / Branching Random Walk. Finally, I will conclude with recent results on models 
which are not even Gaussian, but for which the multiscale treatment still goes through swiftly: 
the directed and undirected first passage percolation in the limit of large dimensions, a.k.a. the (un)directed polymers in random environment.
Joint works with Nicola Kistler, and Marius A. Schmidt.


Talk 2: 14.15-16.00 


Title: Fluctuations and mixing of Internal DLA on cylinders 

Abstract: Internal DLA models the growth of a random discrete set by subsequent aggregation of particles. At each step, a new particle starts inside the current aggregate, and it performs a simple random walk until reaching an unoccupied site, where it settles. The large scale properties of IDLA clusters are by now well understood. In these two talks I will instead focus on Internal DLA on cylinder graphs, seen as a Markov chain on the space of particle configurations. I will present several techniques for bounding the maximal fluctuations of IDLA clusters, which allow one to show that the stationary distribution concentrates on a small subset of the infinite state space. I will then discuss the mixing time of the chain, and its dependence on the choice of the cylinder's base graph.
Tuesday, April 9, 2024
12:00-13:00
HFG 610
Freudenthal topology seminar
Gijs Heuts - TBA
16:00-17:00
HFG - 611
UGC seminar
Chris Keyes (King's College London) - TBA
Thursday, April 11, 2024
10:00-11:00
BBG 017
AG Seminar talk
Younghan Bae -
Abstract: tbd
Monday, April 15, 2024
09:15-17:30
KBG Atlas
Conference “(∞,n)-Categories and their applications”
For talk titles, abstracts,and time slots, you can find a detailed schedule on our conference webpage https://sites.google.com/view/inftyncategories.
Tuesday, April 16, 2024
09:15-17:15
Ruppert Paars
Conference “(∞,n)-Categories and their applications”
For talk titles, abstracts,and time slots, you can find a detailed schedule on our conference webpage https://sites.google.com/view/inftyncategories.
16:00-17:00
HFG 611
Number Theory Talk
Jakob Glas (IST Austria) - TBA
Wednesday, April 17, 2024
09:00-12:45
KBG Pangea
Conference “(∞,n)-Categories and their applications”
For talk titles, abstracts,and time slots, you can find a detailed schedule on our conference webpage https://sites.google.com/view/inftyncategories.
Thursday, April 18, 2024
09:15-17:30
KBG Atlas
Conference “(∞,n)-Categories and their applications”
For talk titles, abstracts,and time slots, you can find a detailed schedule on our conference webpage https://sites.google.com/view/inftyncategories.
10:00-11:00
BBG 017
AG Seminar talk
Andrea Ricolfi - The motive of the Hilbert scheme of points
Abstract: The geometry of Hilbert schemes of points is largely unknown, or known to be pathological in a precise sense. This should in principle make most (naive) invariants essentially inaccessible. In this talk we explain how to obtain a closed formula for the generating function of the motives (classes in the Grothendieck ring of varieties) of Hilbert schemes of points Hilb(X,d) for X a smooth variety of arbitrary dimension, and for fixed number of points d < 9. Work in progress with M. Graffeo, S. Monavari and R. Moschetti.
Friday, April 19, 2024
09:15-14:30
Ruppert Wit
Conference “(∞,n)-Categories and their applications”
For talk titles, abstracts,and time slots, you can find a detailed schedule on our conference webpage https://sites.google.com/view/inftyncategories.
Tuesday, April 23, 2024
12:00-13:00
HFG 610
Freudenthal topology seminar
Léonard Guetta - TBA
16:00-17:00
HFG 611
MI talk
Dirk van Bree - TBA
Wednesday, April 24, 2024
12:00-13:00
MI library
BYOL
15:15-16:45
Active Bystander Training
Internal training, registration required
Thursday, April 25, 2024
16:00-17:00
HFG 611
Applied Math Seminar
Andrei Caragea (MIDS, Katholische Universität Eichstätt)
Title: TBA
Abstract: TBA
Friday, April 26, 2024
14:00-16:30
DDT&G
Luciana Basualdo Bonatto – TBA
Thursday, May 2, 2024
16:00-17:00
HFG 611
Applied Math Seminar
János Flesch (Maastricht) for May 2, Equilibrium in stochastic games with Borel measurable evaluations
Tuesday, May 7, 2024
16:00-17:00
HFG - 611
UGC seminar
Annegret Burtscher (RU) - TBA
Tuesday, May 28, 2024
16:00-17:00
HFG 611
UGC Seminar
Raymond Cheng (Hannover) - TBA
Thursday, June 6, 2024
16:00-17:00
HFG 611
Applied Math Seminar
Bernhard von Stengel (London School of Economics)
Friday, June 7, 2024
11:00-16:00
Mark Kac seminar in mathematical physics and probability
Yvan Velenik (U Geneva) and F. den Hollander (UL)
Thursday, June 27, 2024
16:00-17:00
HFG 611
Applied Math Seminar
Francesca Bartolucci (TU Delft)
Title : TBA
Abstract: TBA
Thursday, September 5, 2024
16:00-17:00
MI talk Yuri Kuznetsov
Title: Recent progress in the numerical bifurcation analysis of delay differential equations
Abstract: TBA