Wochenplan des Fachbereichs Mathematik und Informatik

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kollwit

Anton Wakolbinger, Frankfurt: A decomposition of the Brownian excursion (Oberseminar Mathematische Stochastik)

Mittwoch, 29.01.2020 17:00 im Raum SRZ 117
Mathematik und Informatik

We discuss a realizationwise correspondence between a Brownian excursion (conditioned to reach height one) and a triple consisting of (1) the local time profile of the excursion, (2) an array of independent time-homogeneous Poisson processes on the real line, and (3) a fair coin tossing sequence, where (2) and (3) encode the ordering by height respectively the left-right ordering of the subexcursions. The three components turn out to be independent, with (1) giving a time change that is responsible for the time-homogeneity of the Poisson processes. By the Ray-Knight theorem, (1) is the excursion of a Feller branching diffusion; thus the metric structure associated with (2), which generates the so-called lookdown space, can be seen as representing the genealogy underlying the Feller branching diffusion. We will relate our approach also to earlier work of Aldous and Warren on Brownian excursions conditioned on their local time profile. The lecture is based on joint work with Stephan Gufler and Goetz Kersting.



Angelegt am Dienstag, 12.11.2019 14:13 von kollwit
Geändert am Freitag, 24.01.2020 09:41 von kollwit
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Stochastik
Oberseminare und sonstige Vorträge
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shupp_01

Kolloquium Wilhelm Killing: Prof. Dr. Assaf Rinot (Bar-Ilan): Hindman's theorem and uncountable Abelian groups

Donnerstag, 30.01.2020 16:30 im Raum M5
Mathematik und Informatik

In the early 1970's, Hindman proved a beautiful theorem in additive Ramsey theory asserting that for any partition of the set of natural numbers into finitely many cells, there exists some infinite set such that all of its finite sums belong to a single cell. In this talk, we shall address generalizations of this statement to the realm of the uncountable. Among other things, we shall present a negative partition relation for the real line which simultaneously generalizes a recent theorem of Hindman, Leader and Strauss, and a classic theorem of Galvin and Shelah. Time permits, we shall also discuss the challenges arising in obtaining similar results for non-Abelian groups. This is joint work with David Fernandez-Breton.



Angelegt am Freitag, 11.10.2019 09:56 von shupp_01
Geändert am Montag, 13.01.2020 09:08 von odermann
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Veranstaltungen am Mathematischen Institut
Kolloquium FB10 und Sondervorträge
Kolloquium Wilhelm Killing
Konferenzen+Kolloquien
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srave_01

Patrick Buchfink (Uni Stuttgart): Basis Generation for Symplectic Model Order Reduction

Mittwoch, 05.02.2020 16:15 im Raum M5
Mathematik und Informatik

A popular example for structured, mathematical models are Hamiltonian systems which are known for the characteristic property to preserve the Hamiltonian function. With symplectic model order reduction (symplectic MOR) [2, 3], the dimension of such systems can be reduced while preserving the underlying symplectic structure. In this talk, we investigate a new basis generation technique for symplectic MOR [1] motivated by a symplectic analogue to the Gramian matrix. For the generated bases, we can quantify the error of the reduction with respect to the training data analytically. Furthermore, the new method complements existing basis generation techniques as it is able to compute a symplectic, non-orthogonal basis instead of a symplectic, orthogonal basis. A numerical example in an uncertainty quantification setting will demonstrate the superiority of the new basis generation technique over conventional (symplectic) MOR approaches.

References

[1] P. Buchfink, A. Bhatt, and B. Haasdonk. Symplectic Model Order Reduction with Non-Orthonormal Bases. Mathematical and Computational Applications, 24(2), 2019.

[2] B. Maboudi Afkham and J. Hesthaven. Structure Preserving Model Reduction of Parametric Hamiltonian Systems. SIAM Journal on Scientific Computing, 39(6):A2616-A2644, 2017.

[3] L. Peng and K. Mohseni. Symplectic Model Reduction of Hamiltonian Systems. SIAM Journal on Scientific Computing, 38(1):A1-A27, 2016.



Angelegt am Mittwoch, 15.01.2020 15:52 von srave_01
Geändert am Montag, 27.01.2020 15:09 von srave_01
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Oberseminar Angewandte Mathematik
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elke

Philip Dowerk (Dresden): Analogies between finite- and infinite-dimensional unitary groups. Oberseminar C*-Algebren.

Montag, 20.01.2020 15:15
Mathematik und Informatik



Angelegt am Freitag, 18.10.2019 09:26 von elke
Geändert am Donnerstag, 16.01.2020 08:59 von elke
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Oberseminare und sonstige Vorträge
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elke

Ying-Fen Lin (Queen's University Belfast): Schur multipliers and positive extensions. Oberseminar C*-Algebren.

Dienstag, 14.01.2020 15:15 im Raum SRZ 216
Mathematik und Informatik

I will first introduce scalar-valued and operator-valued Schur multipliers and their partially defined versions, and will provide a Grothendieck-type characterisation of operator-valued Schur multipliers. After a brief introduction to the matrix setting, I will talk about the positive extension problem of Schur multipliers and characterise its affirmative solution in terms of structures on an operator system associated with the domain of the multipliers. This talk will be based on joint papers with R. Levene and I. G. Todorov.



Angelegt am Freitag, 18.10.2019 09:24 von elke
Geändert am Mittwoch, 04.12.2019 09:15 von elke
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Oberseminare und sonstige Vorträge
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gstei_02

Promotions- und Masterfeier des Fachbereiches Mathematik und Informatik

Montag, 17.02.2020 15:00 im Raum Aula des Schlosses
Mathematik und Informatik

Wir werden auf dieser festlichen Veranstaltung mit anschließendem Umtrunk die Absolventen*innen in eine erfolgreiche Zukunft verabschieden und würden uns sehr freuen, wenn Sie an dieser Feier teilnehmen würden.

Promotions- und Masterfeier des Fachbereiches Mathematik und Informatik am 17.02.2020 um 15:00 Uhr in der Aula des Schlosses Schlossplatz 2

Der Dekan des Fachbereichs Mathematik und Informatik Prof. Dr. Xiaoyi Jiang, sowie der Fachbereich Mathematik und Informatik



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Angelegt am Mittwoch, 11.01.2017 11:44 von gstei_02
Geändert am Montag, 27.01.2020 08:35 von vliesche
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Highlights des FB10
Sonstige Vorträge
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weckerm

Dr. Luca Lionni (Radboud-Universität Nijmegen): Scaling limits of random graphs and a proposal for random geometry in dimension higher than two

Dienstag, 18.02.2020 14:15 im Raum SRz 214
Mathematik und Informatik

After explaining the notion of scaling limit of random graphs and the construction of Aldous' continuum random tree and of the Brownian map, I will introduce a new family of random graphs and their limits we called random feuilletages, in a recent paper with J.F. Marckert. These graphs are obtained by identifying points on a random discrete sphere, using a specific random process. We propose with this construction a generalization of the Brownian map in dimensions higher than two.



Angelegt am Mittwoch, 29.01.2020 14:16 von weckerm
Geändert am Mittwoch, 29.01.2020 14:16 von weckerm
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Oberseminare und sonstige Vorträge
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elke

Ringvorlesung 2020: Christoph Böhm: tba.

Mittwoch, 08.04.2020 16:00 im Raum M2
Mathematik und Informatik



Angelegt am Dienstag, 14.01.2020 14:19 von elke
Geändert am Dienstag, 14.01.2020 14:19 von elke
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Sonstige Vorträge