Veranstaltungen

Viele Veranstaltungen werden aktuell online durchgeführt. Informationen zum Zugang finden Sie jeweils unter „mehr” bei dem betreffenden Eintrag.


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Freitag, 21.01.2022, 13:00 Uhr (WIAS-Library)
E-Coffee-Lecture
Dr. Matthias Liero, WIAS:
Coffee-Lecture: Automated building and testing of software projects using the WIAS Gitlab server
mehr ... Veranstaltungsort
Weierstraß-Institut, Hausvogteiplatz 5-7, 10117 Berlin, Library (4. Etage)

Abstrakt
This talk gives an introduction to Gitlab pipelines on the recently installed Gitlab server at WIAS. We will discuss the basic ideas and concepts and go through a simple example of setting up such a pipeline.

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The coffee-lecture will probably take place online

Veranstalter

WIAS Berlin
Mittwoch, 26.01.2022, 10:00 Uhr (Online Event)
Forschungsseminar Mathematische Statistik
Prof. Pierre Jacob, ESSEC Business School, Frankreich:
Some methods based on couplings of Markov chain Monte Carlo algorithms (online talk)
mehr ... Veranstaltungsort
Online Event

Abstrakt
Markov chain Monte Carlo algorithms are commonly used to approximate a variety of probability distributions, such as posterior distributions arising in Bayesian analysis. I will review the idea of coupling in the context of Markov chains, and how this idea not only leads to theoretical analyses of Markov chains but also to new Monte Carlo methods. In particular, the talk will describe how coupled Markov chains can be used to obtain 1) unbiased estimators of expectations and of normalizing constants, 2) non-asymptotic convergence diagnostics for Markov chains, and 3) unbiased estimators of the asymptotic variance of MCMC ergodic averages.

Weitere Informationen
Der Vortrag findet bei Zoom statt: https://zoom.us/j/159082384

Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
Mittwoch, 26.01.2022, 15:15 Uhr (Online Event)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Alexander Mielke, WIAS Berlin:
On two coupled degenerate parabolic equations motivated by thermodynamics (online talk)
mehr ... Veranstaltungsort
Online Event

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Berliner Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)

Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
Mittwoch, 02.02.2022, 10:00 Uhr (Online Event)
Forschungsseminar Mathematische Statistik
Prof. Alessandra Menafoglio, Politecnico Milano , Italien:
Object oriented data analysis in Bayes spaces: From distributional data to the analysis of complex shapes (online talk)
mehr ... Veranstaltungsort
Online Event

Abstrakt
In the presence of increasingly massive and heterogeneous data, the statistical modeling of distributional observations plays a key role. Choosing the 'right' embedding space for these data is of paramount importance for their statistical processing, to account for their nature and inherent constraints. The Bayes space theory is a natural embedding space for (spatial) distributional data, and was successfully applied in varied settings. In this presentation, I will discuss the state-of-the-art methods for the modelling, analysis, and prediction of distributional data, with a particular attention to cases when their spatial dependence cannot be neglected. I will embrace the viewpoint of object-oriented spatial statistics (O2S2), a system of ideas for the analysis of complex data with spatial dependence. All the theoretical developments will be illustrated through their application on real data, highlighting the intrinsic challenges of a statistical analysis which follows the Bayes spaces approach. Applications will cover a varied range of fields, from the assessment of COVID-19 on mortality data to the analysis of complex shapes produced in additive manufacturing.

Weitere Informationen
Der Vortrag findet bei Zoom statt: https://zoom.us/j/159082384

Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
Mittwoch, 02.02.2022, 12:30 Uhr (WIAS-ESH)
Seminar Interacting Random Systems
Dr. Quirin Vogel, NYU Shanghai, China, Volksrepublik:
Infinite loops - The limit of the Feynman representation of the Bose gas (online talk)
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
round 75 years ago, Feynman used path-integration to represent a gas of (interacting) bosons in a finite volume by an ensemble of brownian bridges, aka loops. Bosons exhibit Bose--Einstein condensation - a state of matter in which a macroscopic proportion of the particles occupy the same quantum state. It has been conjectured that the condensate is represented by “infinite” loops. We “verify” this for several cases by proving that the finite volume representation converges to the superposition of finite loops and the random interlacements. Prior knowledge of bosons/mathematical physics is not required for this talk.

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Seminar Interacting Random Systems (Hybrid Event)

Veranstalter
WIAS Berlin
Mittwoch, 02.02.2022, 15:15 Uhr (Online Event)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Upanshu Sharma, Freie Universität Berlin:
Variational structures beyond gradient flows (online talk)
mehr ... Veranstaltungsort
Online Event

Abstrakt
Gradient flows is an important subclass of evolution equations, whose solution dissipates an energy 'as fast as possible'. This distinguishing feature endows these equations with a natural variational structure, which has received enormous attention over the last two decades. In recent years, it has become clear that if the gradient-flow equation originates from an underlying (reversible) stochastic particle system, then often the aforementioned variational structure is an exact decomposition of the large-deviation rate functional for the particle system. However, this decomposition and the corresponding gradient-flow structure breaks down if the underlying particles have additional non-dissipative effects (for instance in the case of non-reversible independent particles), even though the large-deviation rate functional is still available. Using the guiding example of independent non-reversible Markov jump particles, in this talk, I will discuss the various features of the rate functional and how it connects to relative entropy and Fisher information. Furthermore, I will show that if the underlying particle system is augmented with fluxes, then it is possible to derive gradient-flow-type structures in the non-reversible setting.

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Oberseminar “Nichtlineare Partielle Differentialgleichungen” (Langenbach Seminar)

Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
Mittwoch, 09.02.2022, 10:00 Uhr (Online Event)
Forschungsseminar Mathematische Statistik
Prof. Erwan Scornet, Ecole Polytechnique Paris, Frankreich:
Variable importance in random forests (online talk)
mehr ... Veranstaltungsort
Online Event

Abstrakt
Nowadays, machine learning procedures are used in many fields with the notable exception of so-called sensitive areas (health, justice, defense, to name a few) in which the decisions to be taken are fraught with consequences. In these fields, it is necessary to obtain a precise decision but, to be effectively applied, these algorithms must provide an explanation of the mechanisms that lead to the decision and, in this sense, be interpretable. Unfortunately, the most accurate algorithms today are often the most complex. A classic technique to try to explain their predictions is to calculate indicators corresponding to the strength of the dependence between each input variable and the output to be predicted. In this talk, we will focus on variable importances designed for the original random forest algorithm: the Mean Decreased Impurity (MDI) and the Mean Decrease Accuracy (MDA). We will see how theoretical results provide guidance for their practical uses.

Weitere Informationen
Der Vortrag findet bei Zoom statt: https://zoom.us/j/159082384

Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
Mittwoch, 09.02.2022, 12:30 Uhr (WIAS-ESH)
Seminar Interacting Random Systems
Tobias Paul, HU Berlin:
Modelling interactions of mutation, dormancy and transfer
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
Recently, a toy model for the interaction of mutation and horizontal transfer was proposed by Champagnat, Méléard and Tran (2021). We extend their model to include the effects of competition induced dormancy and recover the convergence of the logarithmic population sizes. While the result remains unchanged, the qualitative behaviour of the limiting functions may exhibit properties of the model without dormancy but also entirely new phenomena. As an example we can observe an interesting non-monotonicity in the success of the dormancy traits depending on the strength of the dormancy initiation probability. Furthermore, we will discuss possible extensions and generalizations of the model. (This is joint work with Jochen Blath and András Tóbiás, TU Berlin)

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Seminar Interacting Random Systems (Hybrid Event)

Veranstalter
WIAS Berlin
Donnerstag, 10.02.2022, 16:00 Uhr (Online Event)
Forschungsseminar Mathematische Modelle der Photonik
Shulin Wohlfeil, Ferdinand-Braun-Institut:
Experimental investigations of passively modelocked ridge-waveguide and tapered lasers emitting at 830 nm (online talk)
mehr ... Veranstaltungsort
Online Event

Veranstalter
WIAS Berlin
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik
Mittwoch, 23.02.2022, 12:30 Uhr (WIAS-ESH)
Seminar Interacting Random Systems
Dr. Ana Djurdjevac, Zuse Institute Berlin:
tba
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

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Seminar Interacting Random Systems (Hybrid Event)

Veranstalter
WIAS Berlin
Mittwoch, 09.03.2022, 12:30 Uhr (WIAS-ESH)
Seminar Interacting Random Systems
Alexander Hinsen, WIAS Berlin:
tba
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Weitere Informationen
Seminar Interacting Random Systems

Veranstalter
WIAS Berlin