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Konferenzen und Workshops

Forschungsseminar über diskrete Spektraltheorie

29.05.2024, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Quantum information scrambling and chaos induced by a Hermitian matrix (joint work with Uzy Smilansky)

Sven Gnutzmann

Abstract: Given an arbitrary Hermitian matrix, considered as a finite discrete quantum Hamiltonian, we use methods from graph and ergodic theories to construct a corresponding unitary scattering... 

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08.05.2024, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Anti-Faber-Krahn property for the heat content on metric graphs (or “Building better batteries”)

Matthias Täufer (Hagen)

Abstract: We speak about the heat content at time t on metric graphs. This quantity measures how much mass of a constant initial configuration remains in the graph at time t under the action of the... 

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17.04.2024, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Zero measure Cantor spectrum for Sturmian metric graphs

Gilad Sofer (Technion)

Abstract: A classical result by Belissard et al states that the spectrum of a 1-dimensional Hamiltonian with a Sturmian potential is a singular continuous Cantor set of Lebesgue measure zero. More... 

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10.04.2024, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Effects of time-reversal invariance violation in quantum graphs.

Pavel Exner (Prague)

Abstract: The topic of this talk are quantum graphs with the vertex coupling which does not preserve the time-reversal invariance. As a case study the simplest example with the asymmetry being maximal... 

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31.01.2024, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Deducing properties of graphs from their C*-algebras (and vice versa)

Jonathan Taylor (UP)

Abstract: Given a directed row-finite graph, one may define representations of such a graph in C*-algebras and deduce the existence of a unique C*-algebra that is universal for such representations.... 

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07.12.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Markov chains arising from graphs over ordered fields

Anna Muranova (University of Warmia and Mazury in Olsztyn)

Abstract: In this talk we consider graphs, whose weights belong to an ordered field. It is known, that in the case of real weights every weighted graph defines a Markov chain, whose states are... 

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06.12.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

An embedded trace theorem for infinite metric trees with applications to transmission problems with mixed dimensions.

Konstantin Pankrashkin (Carl von Ossietzky Universität Oldenburg)

Abstract: For a class of weighted infinite metric trees we propose a definition of the boundary trace which maps H^1-functions on the tree to L^2-functions on a compact Riemannian manifold. For a... 

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15.11.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Isospectral magnetic graphs via partitions of numbers

Prof. Olaf Post (Trier)

Abstract: In this talk I will present a construction of discrete magnetic non-isomorphic graphs with isospectral Laplacians.  The construction is based on gluing building blocks according to a... 

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08.11.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Sampling nodes on graphs using Determinantal Point Processes

Simon Barthelmé

Abstract: Joint work with Nicolas Tremblay, Pierre-Olivier Amblard

Determinantal Point Processes (DPPs) are an important class of models of random sets that arise in many areas of mathematics and... 

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01.11.2023, 11:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Jacaranda and the substreetutions

Renaud Leplaideur (Université de la Nouvelle-Calédonie)

Abstract: I will present a new object, called substreetution, which is an extension of substitutions in dynamics (Z-action) to colored trees (free-group action). The main part of the talk will be... 

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18.10.2023, 13:15  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Computing the spectrum of infinite-volume operators from finite patches

Paul Hege (Tübingen)

Abstract: The spectrum of infinite-volume operators is often computed numerically by considering finite sections with Dirichlet or periodic boundary conditions, but such artificial boundary conditions... 

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26.07.2023  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Some Results on Absolutely Continuous Spectrum for Laplacians on Radial Metric Tree Graphs

Dr. Christian Seifert (TUHH)

Abstract: Given a radial metric tree graph, we consider Laplacians with self-adjoint coupling conditions at the vertices. We consider the questions whether presence of absolutely continuous spectrum... 

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12.07.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

The hidden structure in Apery's proof

Ofir David (Technion)

Abstract: In 1978, Apery proved the irrationality of the Riemann zeta value ζ(3) by utilizing a fast converging sequence of rational approximations. However, the details of his proof remained... 

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05.07.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Existence of minimizers for weighted Lp-Hardy inequalities

Ujjal Das (Technion)

The abstract can be found here.

mehr erfahren

28.06.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

The Maslov index in spectral theory: an overview

Selim Sukhtaiev (Auburn University)

Abstract: This talk is centered around a symplectic approach to eigenvalue problems for systems of ordinary differential operators (e.g., Sturm-Liouville operators, canonical systems, and quantum... 

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21.06.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

A diophantine characterization of linear repetitivity in cut and project sets: quantitative results.

Johannes Happich (Leipzig)

Abstract: When comparing the complexity of different aperiodic quasicrystals, it appears that linear repetitivity is a useful property that only applies to the - in some sense - most regular... 

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16.06.2023, 13:15  –  Haus 9, Raum 2.22 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Duistermaat index and eigenvalue interlacing for self-adjoint extensions of a symmetric operator

Gregory Berkolaiko

Abstract:
Eigenvalue interlacing is a tremendously useful tool in linear algebra
and spectral analysis.  In its simplest form, the interlacing
inequality states that a rank-one positive perturbation... 

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14.06.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Spectral minimal partitions of metric graphs: what and why?

James Kennedy

Abstract: SMPs offer a way of dividing a given object (domain, manifold or graph) into a given number of pieces in an ``analytically optimal'' way: typically, one attempts to minimise an energy... 

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07.06.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Gaussian upper heat kernel bounds and Sobolev inequalities on graphs with unbounded geometry

Dr. Christian Rose (Potsdam)

Abstract: On Riemannian manifolds the conjunction of Gaussian upper heat kernel bounds and the volume doubling property of balls are equivalent to Sobolev inequalities in arbitrarily small balls. The... 

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31.05.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Parabolic nonlocal equations with bounded measurable coefficients.

Marvin Weidner (Barcelona)

Abstract: The celebrated De Giorgi-Nash-Moser theory establishes Hölder regularity of solutions to second order equations in divergence form without any regularity assumptions on the coefficients.... 

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24.05.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Spectral properties of quasiperiodic metric graphs

Gilad Sofer (Technion)

Abstract: Sturmian Hamiltonians appear in mathematical physics as popular models for one-dimensional quasicrystals. This family of discrete quasiperiodic Schrödinger operators, including the well... 

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10.05.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Sharp Hardy-type inequalities for non-compact harmonic manifolds and Damek-Ricci spaces.

Florian Fischer (Potsdam)

Abstract: We show various sharp Hardy-type inequalities for the linear and quasi-linear Laplacian on non-compact harmonic manifolds with a particular focus on the case of Damek-Ricci spaces. Our... 

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20.03.2023, 14:00 Uhr  –  Campus Golm, Haus 9, Raum 2.22 + Zoom
Forschungsseminar Diskrete Spektraltheorie

MSc Verteidigung - Graphs with Nilpotent Group Actions and their Drifts

Matti Richter (Potsdam)

Abstract: We study positive generalized eigenfunctions of Schrödinger operators associated to graphs with cocompact group actions of nilpotent groups. For such a graph, we investigate the topological... 

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08.02.2023, 13:30 Uhr  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Regularity results for locally integrable subharmonic functions on local Dirichlet spaces

Prof. Dr. Peter Stollmann (Chemnitz)

Abstract: We report on recent results from a joint work with B. Güneysu, S. Pigola and. G. Veronelli. Using a new notion of subharmonicity we can prove a version of the Braverman-Milatovic-Shubin... 

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18.01.2023, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

A dynamical approach to density theorems for sampling in unimodular groups

Dr. Ulrik Enstad (Stockholm University)

Abstract: Many structured function systems in harmonic analysis arise from the action of a unitary group representation on a single vector in the underlying Hilbert space. A central question is... 

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11.01.2023, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Polya-Szego inequality on 2-D lattice graph.

Shubham Gupta

Abstract: In the continuum, symmetrization inequalities are a fundamental tool in various parts of analysis: variational problems, spectral geometry, mathematical physics just to name a few. In this... 

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14.12.2022, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

The space of Hardy-weights for quasilinear equations: Maz’ya-type characterization and sufficient conditions for existence of minimizers

Prof. Yehuda Pinchover (Technion)

Abstract: Let p ∈ (1,∞) and  Ω⊂ℝN be a domain. 

Let A:=(aij) ∈ Lloc(Ω ; ℝN× N) be  a symmetric and locally uniformly positive definite matrix. Set |ξ|A2:= ∑i,j=1N aij(x) ξi ξj,  ξ ∈ ℝN, and let V be... 

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07.12.2022, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Random simplicial complexes of top bounded degree

Prof. Ron Rosenthal (Technion)

Abstract: In the talk we will introduce a model for random simplicial complexes which are high-dimensional counterparts of random regular graphs.

We will present some results for such random complexes... 

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30.11.2022, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Computing nodal deficiency with a refined spectral flow

Bernard Helffer (Nantes Université)

in collaboration with

G. Berkolaiko, G. Cox, and  M. Persson Sundqvist 

Abstract
Recent work of the authors and their collaborators has uncovered fundamental connections between the... 

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16.11.2022, 13 Uhr  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Spectrum of discrete Laplacian over an ordered field

Anna Muranova (University of Warmia)

Abstract:
We consider discrete normalized Laplacian for finite graphs, whose edge-weights belong to an arbitrary real-closed ordered field. We show that eigenvalues of Laplacian always belong to the... 

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02.11.2022, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

An improved discrete Rellich inequality on the half-line

Borbola Gerhat (Prague)

Abstract

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26.10.2022, 13:00  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

A view on multiple recurrence

Tanja Eisner (Leipzig)

Abstract: We discuss a proof of multiple recurrence for ergodic systems (and thereby of Szemerédi's theorem) being a mixture of three known proofs. It is based on a conditional version of the... 

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13.07.2022, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

On some Mathematical Systems Theory in Banach spaces.

Christian Seifert (Technische Universität Hamburg)

Abstract: Given an abstract Cauchy problem in a Banach space we consider two questions:
1. Can we steer the system to any given state (or to zero, say) in finite time by some inhomogeneity?
2. Can we... 

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06.07.2022, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Semi-linear elliptic inequalities on weighted graphs

Xueping Huang (Nanjing University)

Abstract: We consider the discrete analogue of  semi-linear differential inequalities on weighted graphs. Under some technical conditions, we obtain almost sharp volume growth criteria for the... 

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29.06.2022, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Leptin densities in amenable groups

Christoph Richard (Erlangen)

Abstract: We define a notion of uniform density on translation bounded measures in unimodular amenable locally compact Hausdorff groups, which is based on a group invariant introduced by Leptin in... 

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22.06.2022, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Non-stationary Furstenberg Theorem and Anderson Localization

Anton Gorodetski (UCI)

Abstract: In this talk we will formulate a non-stationary version of the Furstenberg Theorem on random matrix products. As a main application we will discuss how it can be used to prove a... 

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25.05.2022, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Laplacians on Riemann surfaces and Graphs

Noema Nicolussi (Potsdam)

There are many interesting parallels between analysis on Riemann surfaces and graphs. Both settings admit a Laplace operator and the Poisson equation reflects crucial geometric information.

Motivated... 

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18.05.2022, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Uniformity of cocycles

Prof. Daniel Lenz (Universität Jena)

Abstract: Uniformity of continuous SL(2,R) valued cocycles over uniquely dynamical systems has featured in various contexts. Walters asked in '86 whether every uniquely ergodic system admits a... 

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26.01.2022, 13.30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Spectral asymptotic and positivity for singular Dirichlet-to-Neumann operators'

Ali Ben Amor (Gabès, Tunisia)

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11.01.2022, 16:30  –  Haus 9, Raum 2.22 und Zoom
Forschungsseminar Diskrete Spektraltheorie

The landscape law for tight binding Hamiltonians

Shiwen Zhang (University of Minnesota)

Abstract: The localization landscape theory, introduced in 2012 by Filoche and Mayboroda, considers the landscape function u solving Hu=1 for an operator H. The landscape theory has remarkable power... 

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01.12.2021, 13:30  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Schreier graphs of self-similar groups as source of examples in spectral graph theory

Tatiana Smirnova-Nagnibeda (Genf)

Abstract: In this talk we will discuss some results in the spectral theory of infinite graphs obtained using techniques coming from the study of self-similar groups and their actions.

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24.11.2021, 13:30 Uhr  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Graphs with positive spectrum

Bobo Hua (Fudan University Shanghai)

Abstract: We prove sharp l^2 decay estimates of nonnegative generalized subharmonic functions on graphs with positive Laplacian spectrum, which generalizes the result by Li and Wang on Riemannian... 

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10.11.2021, 13:30 Uhr  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Characterizations of Forman curvature

Florentin Münch

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10.11.2021, 13:30 Uhr  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Characterizations of Forman curvature

Florentin Münch (MPI Leipzig)

mehr erfahren

03.11.2021, 13:30 Uhr  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Optimal large scale Gaußian upper bounds for heat kernels of unbounded graph Laplacians

Christian Rose (Universität Bremen)

Abstract: The heat kernel as the minimal fundamental solution of the heat equation is one of the most important objects studied in geometric analysis and encodes the geometry of the underlying space... 

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27.10.2021, 10 Uhr  –  Haus 9, Raum 0.17 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Dynamical systems with pure point spectrum

Daniel Lenz (Jena)

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20.10.2021, 13:30 Uhr  –  Haus 9, Raum 2.22 und Zoom
Forschungsseminar Diskrete Spektraltheorie

Optimal Hardy-type inequalities on lattices in stratified groups

Philipp Hake (Leipzig)

mehr erfahren

13.10.2021, 13:30 Uhr  –  Haus 9, Raum 2.22
Forschungsseminar Diskrete Spektraltheorie

Fiber entropy and algorithmic complexity of random orbits

Elias Zimmermann (Leipzig)

mehr erfahren

09.06.2021, 13:30 Uhr
Forschungsseminar Diskrete Spektraltheorie

Safoura Zadeh (MFO Leibniz Fellow)

Safoura Zadeh (MFO Leibniz Fellow)

Please contact Siegfried Beckus (beckus@uni-potsdam.de) if you are interested to join the talk.

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02.06.2021, 13:30 Uhr  –  Zoom
Forschungsseminar Diskrete Spektraltheorie

Wiener's lemma along subsequences.

Tanja Eisner (Leipzig)

Title: Wiener's lemma along subsequences.

Abstract: We discuss the validity of the classical Wiener lemma and the extremal behaviour of a measure on the unit circle via the behavior of its Fourier... 

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26.05.2021, 13:30 Uhr
Forschungsseminar Diskrete Spektraltheorie

Alexey Klimenko (HSE University Moscow)

Alexey Klimenko

Please contact Siegfried Beckus (beckus@uni-potsdam.de) if you are interested to join the talk.

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19.05.2021, 13:30 Uhr  –  Zoom
Forschungsseminar Diskrete Spektraltheorie

Structure of Delone Sets, a Review

Jean Bellissard (University of Münster)

Please contact Siegfried Beckus (beckus@uni-potsdam.de) if you are interested to join the talk.

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12.05.2021, 13:30 Uhr  –  Zoom
Forschungsseminar Diskrete Spektraltheorie

Path homology on digraphs

Alexander Grigor'yan (University of Bielefeld)

Please contact Siegfried Beckus (beckus@uni-potsdam.de) if you are interested to join the talk.

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26.02. bis 26.02.2020, 12:30  –  Campus Golm, Haus 9, Raum 2.09.2.22
Forschungsseminar Diskrete Spektraltheorie

Harmonic Functions on Graphs with Group Actions

Matti Richter

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22.01. bis 22.01.2020, 12:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.0.14
Forschungsseminar Diskrete Spektraltheorie

Quantitative estimates between the spectra of Schrödinger operators

Dr. Siegfried Beckus (Universität Potsdam)

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11.12. bis 11.12.2019, 12:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.2.22
Forschungsseminar Diskrete Spektraltheorie

Two trace formulae for Hermitian matrices

Uzy Smilansky (Weizmann Institute of Science)

Trace formulae are one of the most important tools in a large number of fields ranging from quantum chaos via spectral geometry, graphs and number theory. Here, I shall present two rather... 

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11.12.2019, 13:45 Uhr  –  Campus Golm, Haus 9, Raum 2.09.2.22
Forschungsseminar Diskrete Spektraltheorie

Bonnet-Myers theorem for Kato-type Ricci curvature conditions

Dr. Christian Rose (MPI Leipzig)

The Kato condition on the negative part of the Ricci curvature turned out to be an appropriate generalization of Lp- curvature conditions that can be used to investigate geometric and topological... 

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27.11. bis 27.11.2019, 12:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.0.14
Forschungsseminar Diskrete Spektraltheorie

On effective impedance of networks

Anna Muranova (Bielefeld University)

Abstract

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20.11. bis 20.11.2019, 12:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.0.14
Forschungsseminar Diskrete Spektraltheorie

On Courant's nodal domain property for linear combinations of eigenfunctions (after P. B\'erard, P. Charron and B. Helffer)

Bernard Helffer (University of Paris-Sud)

Abstract: We revisit  Courant's nodal domain property for linear combinations of eigenfunctions. This property was proven by Sturm (1836) in the case of dimension 1.  Although stated as true for the... 

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13.11. bis 13.11.2019, 12:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.0.14
Forschungsseminar Diskrete Spektraltheorie

Approximating the integrated density of states of random Schrödinger operators - results from empirical process theory

Max Kämper (TU Dortmund)

Random Schrödinger operators are a model for metals with random impurities and this talk will present them for the special case of the Anderson operator on a lattice. We will introduce the integrated... 

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30.10. bis 30.10.2019, 12:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.0.14
Forschungsseminar Diskrete Spektraltheorie

Infinite Quantum Graphs

Noema Nicolussi (University of Vienna)

Abstract

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16.10.2019, 12:30  –  Campus Golm, Haus 9, Raum 2.09.0.14
Forschungsseminar Diskrete Spektraltheorie

Nodal statistics of quantum graph eigenfunctions

Prof. Dr. Ram Band (Israel Institute of Technology - Technion)

We discuss the number of zeros of Laplacian eigenfunctions on a metric (quantum) graph.
The n-th eigenfunction has at least n-1 zeros and at most n-1+\beta zeros, where \beta is the number of graph... 

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27.02.2019, 13:00 Uhr  –  Campus Golm, Haus 9, Raum 2.09.1.10
Forschungsseminar Diskrete Spektraltheorie

Interpolation Theory for Singular Integrals on Spaces of Homogeneous Type

Philipp Bartmann

We will discuss aspects of classical interpolation theory including properties of the Hardy–Littlewood maximal function and Marcinkiewicz’s interpolation theorem. Further, we will establish the... 

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20.02.2019, 16:00 Uhr  –  Campus Golm, Haus 9, Raum 2.09.1.10
Forschungsseminar Diskrete Spektraltheorie

Globale topologische Poincaré Ungleichung auf Graphen

Jonas Grünberg

 

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30.01.2019, 16:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.1.10
Forschungsseminar Diskrete Spektraltheorie

Parabolic Harnack Inequality, Gaussian Estimates and Geometric Properties on Graphs

Christian Scholz

Consider a countable set and a weighted, uniformly locally finite graph. In his paper "Parabolic Harnack inequality and estimates of Markov chains on graphs", Delmotte proves that parabolic Harnack... 

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09.01.2019, 16:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.1.10
Forschungsseminar Diskrete Spektraltheorie

Neumann problems on graphs

Michael Schwarz

Abstract

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19.12.2018, 16:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.1.10
Forschungsseminar Diskrete Spektraltheorie

Spectral asymptotics of Robin Laplacians on polygonal domains

Magda Khalile (Leibniz Universität Hannover)

Abstract

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05.12.2018, 16:15 Uhr  –  Campus Golm, Haus 9, Raum
Forschungsseminar Diskrete Spektraltheorie

Inference of Phylogenetic Trees from Homology-Relations

Marc Hellmuth (Universität Greifswald)

Phylogenomics aims at finding plausible hypothesis about the evolutionary history of gene or species based on genomic sequence information. Genes are passed from generation to generation to the... 

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28.11.2018, 16:30 Uhr  –  Campus Golm, Haus 9, Raum 2.09.1.10
Forschungsseminar Diskrete Spektraltheorie

A Riesz' Decomposition Theorem for Schrödinger Operators On Graphs

Florian Fischer (Universität Potsdam)

In the classical potential theory on Euclidean space and in the potential theory of transient Markov chains a unique decomposition of superharmonic functions in a harmonic and a potential part is... 

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14.11.2018, 16:15 Uhr  –  Campus Golm, Haus 9, Raum 2.09.1.10
Forschungsseminar Diskrete Spektraltheorie

Kato-type curvature conditions and the Cheeger constant

Christian Rose (Technische Universität Chemnitz)

We show that if the negative part of the Ricci curvature of a compact manifold is in the Kato-class, the Cheeger constant of the manifold can be bounded below by a positive constant. This is obtained... 

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07.11.2018, 16:15 Uhr  –  Campus Golm, Haus 9, Raum 2.09.1.10
Forschungsseminar Diskrete Spektraltheorie

Shnol type theorem for the Agmon ground state - the discrete setting

Siegfried Beckus (Universität Potsdam)

The celebrated Shnol theorem asserts that every polynomially bounded generalized eigenfunction for a given energy E associated with a Schrödinger operator H implies that E is in the L2-spectrum of H.... 

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19.01.2017, 10:30 Uhr  –  Campus Golm, Haus 9, Raum 1.10
Forschungsseminar Diskrete Spektraltheorie

A transport metric for non-local Dirichlet forms and gradient flows of the entropy

Melchior Wirth

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12.01.2017, 10:30 Uhr  –  Campus Golm, Haus 9, Raum 1.10
Forschungsseminar Diskrete Spektraltheorie

First order calculus for Dirichlet forms and some applications to PDE

Michael Hinz (Bielefeld)

In this talk we review the definitions of items of vector calculus based on Dirichlet forms and mention connections to graph Laplacians and to non-local and local operators on metric measure spaces.... 

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05.01.2017, 10:30 Uhr  –  Campus Golm, Haus 9, Raum 1.10
Forschungsseminar Diskrete Spektraltheorie

Audible and inaudible curvature invariants

Dorothee Schüth (HU Berlin)

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08.12.2016, 10:30 Uhr  –  Campus Golm, Haus 9, Raum 1.10
Forschungsseminar Diskrete Spektraltheorie

Discrete Ricci curvature via geodesic convexity of the entropy

Jan Maas (IST Austria)

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01.12.2016, 10:15 Uhr  –  Campus Golm, Haus 9, Raum 1.10
Forschungsseminar Diskrete Spektraltheorie

Courant's nodal domain theorem for regular Dirichlet forms

Michael Schwarz

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24.11.2016, 10:30 Uhr  –  Campus Golm, Haus 9, Raum 1.10
Forschungsseminar Diskrete Spektraltheorie

Rigidity properties of the hypercube via Bakry Emery curvature

Florentin Münch

We give rigidity results for discrete Bonnet-Myers diameter bound and Lichnerowicz eigenvalue estimate. Both inequalities are sharp if and only if the underlying graph is a hypercube.  The proofs use... 

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03.11.2016, 10:00 Uhr  –  Campus Golm, Haus 9, Raum 1.10
Forschungsseminar Diskrete Spektraltheorie

Exactness of Dynamical Systems and Convergence of Semigroups

Moritz Gerlach

This talk aims at completing the picture how exactness of dynamical systems is related to the asymptotic behavior of the Perron-Frobenius operator. In doing so, we give a mixing-like description of... 

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27.10.2016, 11:00 Uhr  –  Campus Golm, Haus 9, Raum 1.10
Forschungsseminar Diskrete Spektraltheorie

Nichtkommutative Quasikristalle

Felix Pogorzelski (Technion Haifa)

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19.07.2016, 12:30  –  Campus Golm, Haus 9, Raum 0.13
Forschungsseminar Diskrete Spektraltheorie

Essential selfadjointness and the l^2 Liouville property

Radoslaw Wojciechowski (CUNY)

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05.07.2016, 12:30  –  Campus Golm, Haus 9, Raum 0.13
Forschungsseminar Diskrete Spektraltheorie

Ricci curvature and eigenvalue estimate for the magnetic Laplacian on manifolds

Shiping Liu (Durham)

I will discuss a Buser type and a Lichnerowicz type eigenvalue estimates for the magnetic Laplacian on a closed Riemannian manifold. Those are motivated by our previous ... 

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23.06.2016, 10:30 Uhr  –  Campus Golm, Haus 5, Raum 1.04
Forschungsseminar Diskrete Spektraltheorie

On the spectrum of operator families on discrete groups over minimal dynamical systems

Christian Seifert (Hamburg Harburg)

We consider families of bounded linear operators on \ell_p-spaces of discrete groups, parametrized by a dynamical system. By using limit operator techniques, we show that all the operators from that... 

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16.06.2016, 14:15 Uhr  –  Campus Golm, Haus 14, Raum 0.38
Forschungsseminar Diskrete Spektraltheorie

Averaging principles: From a microscopic to a macroscopic point of view

Markus Kunze (Konstanz)

We consider diffusion problems in a domain which is further subdivided by semi-permeable membranes. Such problems frequently occur in applications in biology, for example when studying the... 

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07.06.2016, 12:15  –  Campus Golm, Haus 9, Raum 0.13
Forschungsseminar Diskrete Spektraltheorie

Seminar "Mengentheoretische Topologie": Der Satz von Tychonoff

Martin Schuhmacher

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31.05.2016, 12:30  –  Campus Golm, Haus 9, Raum 0.13
Forschungsseminar Diskrete Spektraltheorie

Complex line bundles over simplicial complexes

Felix Knöppel (TU Berlin)

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10.05.2016, 12:30  –  Campus Golm, Haus 9, Raum 0.13
Forschungsseminar Diskrete Spektraltheorie

Heat kernel estimates on measure spaces and the relative compactness of perturbations by potentials

Batu Güneysu (HU Berlin)

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03.05.2016, 12:30  –  Campus Golm, Haus 9, Raum 0.13
Forschungsseminar Diskrete Spektraltheorie

Agmon-Abschätzungen für Differenzen-Operatoren

Elke Rosenberger (Potsdam)

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26.04.2016, 12:30 Uhr  –  Campus Golm, Haus 9, Raum 0.13
Forschungsseminar Diskrete Spektraltheorie

Continuous variation of the spectrum: A characterization and a tool

Siegfried Beckus (University Jena)

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04.02.2016, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

Integral Ricci curvature bounds and the Kato class on Riemannian manifolds

Christian Rose (TU Chemnitz)

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21.01.2016, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

Asymptotic behaviour of the Hodge-Laplacian spectrum on graph-like manifolds

Michela Egidi (TU Chemnitz)

In this talk (joint work with O. Post) we consider a family of compact, oriented and connected n-dimensional manifolds constructed according to the ... 

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14.01.2016, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

The spectrum of the graph p-Laplacian operator

Francesco Tudisco (Saarland University)

This introductory talk will focus on the eigenvalues and eigenfunctions of the graph p-Laplacian. We shall discuss two definitions of the eigenpairs that come as a natural generalization of the linear... 

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10.12.2015, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

Eventual Positivity of Operator Semigroups

Jochen Glück (Universität Ulm)

Let T = (T(t)) be a C_0-semigroup on some function space or, more generally, on a Banach lattice E. The semigroup T is called positive if T(t)f \ge 0 for each 0 \le f \in E and for each t \geg 0.... 

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03.12.2015, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

On the Liouville property of harmonic functions

Jun Masamune (Tohoku University)

When every harmonic function belonging to a space $E$ of functions is identically constant, we say that the $E$-Liouville property holds true. There are different types of Liouville property according... 

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26.11.2015, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

News about entropy

Felix Pogorzelski (Technion Haifa)

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19.11.2015, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

Energy Forms

Marcel Schmidt (University Jena)

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05.11.2015, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

Dirichlet Forms on Canonically Compactifiable Graphs

Michael Schwarz (Potsdam)

We consider weighted graphs with an infinite set $X$ of vertices such that every function of finite energy is bounded. For each of these graphs there is a compact set $K$ containing $X$ as a dense... 

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29.10.2015, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

Curvature and Diffusion on Graphs -- Non-linear Curvature Dimension Conditions vs. Li-Yau Inequality

Florentin Münch (Potsdam)

We introduce a new version of curvature dimension inequality. We use this to prove a logarithmic Li-Yau inequality on graphs. To formulate this inequality, we use a non-linear ariant of the calculus... 

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22.10.2015, 12:30 Uhr  –  Campus Golm, Haus 5, Raum 1.12
Forschungsseminar Diskrete Spektraltheorie

Spectral Convergence of Empirical Graph Laplacians

Moritz Gerlach (Potsdam)

Given a finite sequence of n samples drawn independently at random from a compact submanifold of the Euclidean space, we study the asymptotic behavior of Laplacians on the epsilon-neighborhood graph... 

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