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Tuesday, 21.02.2017, 15.00 Uhr (WIAS-406)
Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
A. Locatelli, Universität Potsdam:
Adaptation to noise parameters in non-parametric active learning
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Abstract
In this talk, I will present the non-parametric Active Learning classification setting already studied in Minsker (2012a) and show non-trivial strategies that can adapt to the smoothness of the regression function as well as the noise parameter and that require strictly weaker Assumptions than in previous work. We will first study the deterministic setting (i.e. one has access to the true value of the regression function) to build intuition, and then move on to the stochastic setting (noisy binary classification).

Host
WIAS Berlin
Thursday, 23.02.2017, 09.30 Uhr (WIAS-406)
FG Stochastische Systeme mit Wechselwirkung
Dr. T. Hulshof, University of Technology, Niederlande:
Higher order corrections for anisotropic bootstrap percolation
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Abstract
Bootstrap percolation is a very simple model for growth from a random initial configuration on finite lattices. The model has many applications, for instance to model the spread of infections and to model magnets at low temperatures, to name two, but it is also interesting from a purely mathematical perspective. The model parameter has a critical value, at which the behaviour changes sharply. One interesting feature of bootstrap percolaton is a phenomenon called the ?bootstrap paradox? which relates to a big discrepancy between numerical and theoretical estimates of the critical value of bootstrap percolation models. I will discuss work in progress in which we give the most accurate theoretical estimate for the critical value of any bootstrap model to date, compare it with new numerical estimates, and show how it (tentatively) resolves the paradox. This talk is based on joint work with Hugo Duminil-Copin and Aernout van Enter, and on work with Robert Fitzner.

Host
WIAS Berlin