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## April 2016

### ALOP-Colloquium with Serkan Gugercin

On 18 April Serkan Gugercin from the College of Science at Virginia Tech will join the ALOP-Colloquium and present his recent work.

Find out more »## May 2016

### ALOP-Colloquium with Sven Krumke

On May 9, 2016 Sven Krumke from the Technische Universität Kaiserslautern will join the ALOP-Colloquium and present his recent work. At 15:45 there will be a coffee hour in E10. The presentation will take place in HS10 at 16:15.AbstractWe present a generalization of the fractional packing framework introduced by Garg and Koenemann (2007) that incorporates Megiddo's (1979) parametric search technique: Given a polyhedral cone that is finitely generated by a (possibly exponential-size) set of non-negative vectors and given an oracle…

Find out more »### ALOP-Colloquium with Martin Berggren

On May 23 Martin Berggren from the Department of Computing Science at Umeå University will join the ALOP-Colloquium and present his recent work. At 15:45 there will be a coffee hour in E10. At 16:15 the presentation will take place in HS10.AbstractA system involving acoustic or electromagnetic wave motion can often be characterized using anassociated balance law that involves an energy density, a power flux through surfaces, and various lossterms. Devices that guide such wave motion can be thought of…

Find out more »## June 2016

### ALOP-Colloquium with Immanuel Bomze

On June 13, 2016, Immanuel Bomze from the University of Vienna will join the ALOP-Colloquium and present his recent work. At 15:45 there will be a coffee hour in E10. At 16:15 the presentation will take place in HS10.Second-order local optimality conditions involving copositivity of the Hessian of the Lagrangian on the reduced (polyhedral) tangent conehave the advantage that there is only a small gap between sufficient (the Hessian is strictly copositive) and necessary (the Hessian is copositive) conditions. In this…

Find out more »### ALOP-Colloquium with Felix Kuebler

On June 20, 2016, Felix Kuebler from the University Zurich, Institute of Banking and Finance will join the ALOP-Colloquium and present his recent work. At 15:45 there will be a coffee hour in E10. At 16:15 the presentation will take place in HS10.Recursive equilibria in dynamic economies with stochastic production (mit Johannes Brumm und Dominika Kryczka)In this paper, we prove the existence of recursive equilibria in stochastic production economies with infinitely lived agents and incomplete financial markets. We consider a general…

Find out more »### ALOP-Colloquium with Peter Deuflhard

On June 27, 2016, Prof. Dr. Dr. h.c. Peter Deuflhard from the Université Pierre et Marie Curie (UPMC) will join the ALOP-Colloquium and present his recent work. At 15:45 there will be a coffee hour in E10. At 16:15 the presentation will take place in HS10. THE GRAND FOUR. Affine Invariant Newton Methods for Nonlinear Problems Four affine invariance classes (affine covariance, affine contravariance, affine conjugacy, affine similarity) for nonlinear problems lead to four different classes of adaptive Newton algorithms. Affine covariance applies…

Find out more »## July 2016

### ALOP-Colloquium with Andreas Brieden

On July 4, 2016, Prof. Dr. Andreas Brieden from the Universität der Bundeswehr Münchenwill join the ALOP-Colloquium and present his recent work. At 15:45 there will be a coffee hour in E10. At 16:15 the presentation will take place in HS10.Polytope, Bionade und AntidepressivaDer hohe Stellenwert der Algorithmischen Optimierung (oder auch Mathematischen Optimierung bzw. Angewandten Algorithmischen Mathematik) erklärt sich nicht allein durch eine Fülle wertvoller theoretischer Resultate. Insbesondere ihr Beitrag bei der erfolgreichen Lösung einer Vielzahl von realökonomischen Herausforderungen unterstreicht ihre Bedeutung.…

Find out more »## October 2016

### ALOP Colloquium with Prof. Dr. Lars Grasedyck

On October 4, 2016, Prof. Dr. Lars Grasedyck from the RWTH University Aachen will join the ALOP-Colloquium and present his recent work. At 15:45 there will be a coffee hour in E10. At 16:15 the presentation will take place in HS9.Hierarchical Low Rank Tensor Formats AbstractThe first part of this talk on hierarchical low rank formats starts with a general introduction to notions of rank in higher dimensions, namely Canonical Polyadic (CP), Tucker, TT and Hierarchical Tucker (HT) ranks and the…

Find out more »### ALOP Colloquium with Prof. Dr. Harbir Antil

On October 5, 2016, Prof. Dr. Harbir Antil from George Mason University will join the ALOP-Colloquium and present his recent work. At 15:45 there will be a coffee hour in E10. At 16:15 the presentation will take place in HS10.Optimal control of fractional order PDEsAbstractDiffusion is the tendency of a substance to evenly spread into an available space, and is one of the most common physical processes. The classical models of diffusion lead to well-known equations. However, in recent times, it…

Find out more »### ALOP Colloquium with Prof. Dr. Georg Pflug

On October 24, 2016, Prof. Dr. Georg Pflug from the University of Vienna will join the ALOP-Colloquium and present his recent work:Multistage Stochastic Optimization: Approximation, bounds and ambiguityAbstractMultistage stochastic programs are - in contrast to two-stage programs - difficult variational problems for which solutions can be found only in exceptional cases. For this reason, we have to approximate them by easier programs. We show how a distance between these problems can be found by a variant of a transportation distance, which…

Find out more »## November 2016

### ALOP Colloquium with Prof. Dr. Maria Dolores Ugarte

On November 7, 2016, Prof. Dr. Maria Dolores Ugarte from the Universidad Publica de Navarra will join the ALOP-Colloquium and present her recent work: Title: Analyzing cancer mortality in small areas using Bayesian B-splines Abstract: In recent years, models incorporating splines have been considered for smoothing risks in disease mapping. Although these models are very fexible, they can be computationally demanding in certain cases. In this talk, several models including one, two, and three dimensional B-splines (penalized or un-penalized) are proposed…

Find out more »### ALOP Colloquium with Dr. Benedikt Wilbertz

On November 28, 2016, Dr. Benedikt Wilbertz will join the ALOP-Colloquium and present his recent work entitled Hot Topics in Machine LearningAbstractThe history of machine learning goes back to the late 50s, when the first perceptron models were created to build machines that lean from observations.It took until the mid 80s that Yann LeCun constructed a neural network which can be considered as the first production read application of modern machine learning.Since then, the field shifted its focus more towards…

Find out more »### ALOP-Colloquium with Prof. Dr. Andreas Krause

On Wednesday, November 30, 2016, Prof. Dr. Andreas Krause from the ETH Zurich will join the ALOP-Colloquium and present his recent work entitledSubmodularität und Machine Learning At 13:45 there will be a coffee hour in E-10. At 14:00 the presentation will take place in HS9.

Find out more »## January 2017

### ALOP-Colloquium with Prof. Dr. Armin Fuegenschuh

On Thursday, January 19, 2017, Prof. Dr. Armin Fuegenschuh from the Helmut Schmidt Universitaet Hamburg will join the ALOP-Colloquium and present his recent work entitledDesign Issues for Magnetic Rulers We deal with the design of a magnetic ruler as an absolute positioning system. Trapezoid-shaped magnetic areas are placed side by side, so that the resulting pattern enables a unique encoding of each position up to a micrometer level. The problem of finding a longest-possible ruler from a set of elementary…

Find out more »### ALOP-Colloquium with Dr. Roland Hildebrand

On Thursday, January 23, 2017, Dr. Roland Hildebrand from the University of Grenoble will join the ALOP-Colloquium and present his recent work Element-wise functions preserving positivity of matrices At 15:45 there will be a coffee hour in E10. The presentation will take place in HS9 at 16:15.

Find out more »## February 2017

### ALOP Colloquium with Dr. Bart Vandereycken

On Monday, February 6, 2017, Dr. Bart Vandereycken from the University of Geneva will join the ALOP-Colloquium and present his recent work Manifold optimization for low rank matrix and tensor completionThe minimisation of a smooth objective function subject to (matrix) rank constraints can sometimes be very effectively solved by methods from Riemannian optimisation. This is for instance the case with the low-rank matrix and tensor completion problems However, the standard theory of Riemannian optimisation leaves some questions unanswered regarding its theoretical and practical…

Find out more »## April 2017

### ALOP Colloquium with Dr. Marta D’Elia

On Wednesday, April 19, 2017, Dr. Marta D'Elia from the Computer Science Research Institute at Sandia National Laboratories will join the ALOP-Colloquium and present her recent work entitled A coupling strategy for nonlocal and local models with applications to static peridynamics and classical elasticityABSTRACT: The use of nonlocal models in science and engineering applications has been steadily increasing over the past decade. The ability of nonlocal theories to accurately capture effects that are difficult or impossible to represent by local Partial Differential…

Find out more »### ALOP Colloquium with Prof. Florian Jarre

On Monday, April 24, 2017, Prof. Florian Jarre from the Heinrich Heine Universität Düsseldorf will join the ALOP-Colloquium and present his recent work "The Max-Cut-Polytop"AbstractThe max-cut-polytope arises from a simple reformulation of the problem of finding the maximum cut in a graph with given edge weights. Unfortunately, the exact pre-presentation of the cut polytope is not tractable unless NP = Co-NP.We discuss two different representations and inner and outer nonlinear approximations of the max-cut polytope leading to the anticipation that solving…

Find out more »## May 2017

### ALOP Colloquium with Prof. Andreas Frommer

On Monday, May 15 2017, Prof. Andreas Frommer of Bergische Universität Wuppertal will join the ALOP-Colloquium and present his recent work entitled Matrix functions - computation and convergence for Krylov subspace based methods Abstract: f(A)b, the action of the function f of a matrix A on a vector b, is required in many applications, for example in exponential integrators, where f = exp or in lattice QCD where f(z) = z-α; α ϵ (0, 1). Typically, A is large and sparse, so…

Find out more »### ALOP Colloquium with Prof. François Glineur

On Monday, May 29, 2017, Prof. François Glineur from the Université catholique de Louvain will join the ALOP-Colloquium and present his recent work entitledPerformance estimation of first-order methods for composite convex optimizationComposite convex optimization consists in the minimization of a convex objective function equal to the sum of several convex functions with different properties, for example a smooth term and a nonsmooth term. We consider a large class of first-order methods designed to solve such composite problems, which rely on specific…

Find out more »## June 2017

### ALOP Colloquium with Prof. Lorenz T. (Larry) Biegler

On Friday, June 9 2017, Prof. Lorenz T. (Larry) Biegler, will join the ALOP-Colloquium and present his recent work. Lorenz T. (Larry) Biegler is currently the Head and Bayer University Professor of Chemical Engineering at Carnegie Mellon University. His research interests lie in computer aided process engineering (CAPE) and include flowsheet optimization, optimization of systems of differential and algebraic equations, reactor network synthesis and algorithms for constrained, nonlinear process control. Projects in these areas include analysis and development of nonlinear programming…

Find out more »### ALOP Colloquium with Prof. Gabriel Wittum

On Monday, June 12, 2017, Prof. Gabriel Wittum of King Abdullah University of Science and Technology will join the ALOP-Colloquium and present his recent work entitledSimulation of Neuronal Signal ProcessingThe crucial feature of neuronal ensembles is their high complexity and variability. This makes modelling and computation very difficult, in particular for detailed models based on first principles. The problem starts with modelling geometry, which has to extract the essential features from those highly complex and variable phenotypes and at the…

Find out more »### ALOP Colloquium with Dr. Giorgio Ferrari

On Monday, June 26 2017, Dr. Giorgio Ferrari with Bielefeld University will join the ALOP-Colloquium and present his recent work entitled On the Optimal Management of Public Debt: a Singular Stochastic Control Problem Consider the problem of a government that wants to reduce the debt-to-GDP (gross domestic product) ratio of a country. The government aims at choosing a debt reduction policy which minimises the total expected cost of having debt, plus the total expected cost of interventions on the debt ratio.…

Find out more »## September 2017

### ALOP Colloquium with Prof. Tim Kelley

On Friday, September 8, 2017, Prof. Tim Kelley of North Carolina State University will join the ALOP-Colloquium and present his recent work entitled Anderson Acceleration Abstract: We will discuss recent results on the local convergence of Anderson Acceleration. This is an algorithm for accelerating the convergence of fixed point or Picard iteration. In this talk we will discuss the first convergence results for the method, illustrate the results with an application to radiative transport, discuss issues with…

Find out more »## October 2017

### ALOP-Colloquium with Prof. MK (Mapundi) Banda

On Monday, October 23, 2017, at 16:00 Prof. MK (Mapundi) Banda of the University of Pretoria will join the ALOP-Colloquium and present his recent work entitledOptimal Control, Stabilization and Parameter Identification for evolution modelsEvolution models governed by the time-dependent partial differential equations will be considered. In this talk, we will present some ideas on optimal control, boundary stabilization and parameter identification for a selection of such models. For instance, boundary information will be used to stabilise or to identify parameters of the…

Find out more »## November 2017

### ALOP-Colloquium with Dr. Venera Khoromskaia

Dr. Verena Khoromskaia of the Max-Planck-Institute für Mathematik in den Naturwissenschaften will join the ALOP-Colloquium and present her recent work entitledTensor numerical methods in computational quantum chemistryon Monday, November 6, 2017 at 16:00. We will meet for coffee prior to her presentation at 15:45 in room E10. The presentation will take place in HS9.

Find out more »### ALOP-Colloquium with Prof. Boris N. Khoromskij

On Monday, November 6, 2017, Prof. Dr. Boris Khoromskij from the Max-Planck-Institute für Mathematik in den Naturwissenschaften will join the ALOP-Colloquium and present his recent work entitledTensor numerical methods for multi-dimensional PDE's and in data modelingon Monday, November 6, 2017 at 17:00. The presentation will take place in HS9.

Find out more »### ALOP-Colloquium with Prof. John Pearson

On Monday, November 20, 2017, at 16:00 Prof. John Pearson of School of Mathematics, The University of Edinburgh will join the ALOP-Colloquium and present his recent work entitledFour Perspectives on Preconditioning PDE-Constrained Optimization ProblemsAbstract:PDE-constrained optimization problems have a wide range of applications across numerical mathematics and applied science, so it is important to develop fast and feasible methods to solve such problems. We employ preconditioned iterative methods to tackle the large and sparse matrix systems that arise from their discretization,…

Find out more »## December 2017

### ALOP-Colloquium with Prof. Ekaterina Kostina

On Monday, December 4, 2017, at 16:00 Prof. Ekaterina Kostina of Heidelberg University will join the ALOP-Colloquium and present her recent work entitled Optimization-Based Model Validation - a Mathematical Technology of High ImpactValidated dependable mathematical models are of ever growing importance in science and engineering, and today also driven by a serious demand of the industry. Apart from providing scientific insight into complex nonlinear processes, mathematical models are fundamental for process simulation, optimization and control. In this context the new paradigmatic…

Find out more »## January 2018

### ALOP-Colloquium with Prof. Andrea Walther

On Monday, January 22, 2018, at 16:00 Prof. Andrea Walther of Paderborn University will join the ALOP-Colloquium and present her recent work entitled:Recent progress in the optimization of piecewise smooth functionsIn a previous paper, we derived first and second order convexity conditions for a large class of piecewise smooth functions.In that analysis based on piecewise linearization, a key assumption was the Linear Independence Kink Qualification (LIKQ), a generalization of the Linear Independence Constraint Qualification (LICQ) known from smooth nonlinear optimization.…

Find out more »## February 2018

### ALOP- Colloquium with Prof. Fredi Troeltzsch

On Tuesday, February 6, 2018, at 12:00 Prof. Fredi Tröltzsch of TU Berlin will present his recent work entitled Optimal and Feedback Control of some Reaction-Diffusion EquationsThe optimal control of some systems of nonlinear reaction-diffusion equations is considered including several important equations of mathematical physics. In particular, equations are covered that develop traveling wave fronts, spiral waves, scroll rings, or propagating spot solutions. Well-posedness of the system, differentiability of the control-to-state mapping, and optimality conditions of first and second order are…

Find out more »### ALOP-Colloquium with Prof. Dr. Geovani Grapiglia

Prof. Dr. Geovani Grapiglia of the Universidade Federal do Parana in Curitiba, PR, Brasil will visit with the students of the RTG ALOP to discuss his research as well as speak during our colloquium on the topic of Improved Optimization Methods for Image Registration Problems Abstract: In many applications, multiple images of the same subject are obtained at different moments in time and under different conditions. The goal is to identify changes in the subject over time. For a…

Find out more »## March 2018

### Prof. Juan Vera and Olga Kuryatnikova of Tilburg University to visit in March

Prof. Juan Vera and Olga Kuryatnikova of Tilburg University are scheduled to visit the Research Training Group ALOP in March for research collaboration. During their visit, they will speak on the following topics: Copositive certificates of non-negativity (Prof. Juan Vera) Abstract: Sum-of-squares (sos) certificates of non-negativity, such as Putinar's Positivstellensatz, have been used to obtain powerful numerical techniques to solve polynomial optimization (PO) problems. Using such certificates, hierarchies of semidefinite relaxations are obtained for PO. Usually the use…

Find out more »## April 2018

### ALOP-Colloquium with Prof. Michael Günther

On Monday, April 16, 2018, at 16:00 Prof. Michael Günther of Bergische Universität Wuppertal will join the ALOP-Colloquium and present his recent work entitled Effiziente numerische Simulation multiphysikalischer Systeme Multiphysikalische Systeme werden oft durch Modelle beschrieben, die DAE-Netzwerkmodelle mit partiellen Differentialgleichungen über geeignete Randbedingungen und Quellterme koppeln. Nach Semidiskretisierung im Ort hat man es dann mit großen, gekoppelten DAE-Sytemen zu tun. In diesem Vortrag werden verschiedene Ansätze zu deren effizienter numerischer Simulation besprochen: Multirate-Verfahren und dynamsche Iteration. The presentation…

Find out more »## May 2018

### ALOP-Colloquium with Kerstin Lux

On Monday, May 7, 2018, at 16:00, Kerstin Lux of Universität Mannheim will join the ALOP-Colloquium and present her recent work entitled "Optimal inflow control in supply systems with uncertain demands." Abstract: We are concerned with optimal control strategies subject to uncertain demands. They have a broad range of applications. Taking uncertainty into account becomes more and more important in many areas. In the context of supply chain management, a need for control strategies taking these uncertainties into account naturally…

Find out more »### ALOP-Colloquium with Prof. Partha Lahiri

On Monday, May 14, 2018, at 16:00, Prof. Partha Lahiri of the University of Maryland College Park will join the ALOP-Colloquium and present his recent work entitled "Big data in official statistics." Abstract: The demand for various socio-economic, transportation, and health statistics for small geographical areas is steadily increasing at a time when survey agencies are desperately looking for ways to reduce costs to meet fixed budgetary requirements. In the current survey environment, the application of standard sample survey methods…

Find out more »## June 2018

### ALOP-Colloquium with Mehiddin Al-Baali

On Thursday, June 28, 2018, at 16:00 c.t. Prof. Mehiddin Al-Baali, Department of Mathematics and Statistics, Sultan Qaboos University, Muscat, Oman will present his recent work entitled On the Damped Technique, Self-Scaling and their Combination when Introduced to the Broyden Family of Methods for Unconstrained Optimization Recently, we have extended the damped-technique in the modified BFGS method of Powell for constrained optimization to the Broyden family of quasi-Newton methods for unconstrained optimization. Appropriate choices for the damped parameter will be…

Find out more »## October 2018

### ALOP Colloquium with Arie M.C.A. Koster

On Monday, October 29, 2018 at 16:00 c.t. Prof. Dr. Ir. Arie M.C. A. Koster of RWTH Aachen will present his recent work entitled Robust Combinatorial Optimization - New Problems and Solutions Abstract: The growing need to deal with uncertainties in optimization processes has lead to many new research directions. In robust optimization, an uncertainty set has to be defined containing all scenarios to be considered. Availability of historical data often suggests the use of a discrete or polyhedral uncertainty…

Find out more »## November 2018

### ALOP Colloquium with Caroline Geiersbach

On Monday, November 26, 2018 at 16:00 c.t. Caroline Geiersbach of Universität Wien will present her recent work entitled Stochastic Approximation for Shape Optimization The presentation will take place in HS 9. Please join us for coffee at 15:45 in E10.

Find out more »## December 2018

### ALOP Colloquium with Frank Vallentin

On Monday, December 3, 2018 at 16:00 c.t. Prof. Dr. Frank Vallentin of Universität Köln will present his recent work entitled "Chromatic numbers of geometric graphs" Abstract: A classical problem in discrete geometry (due to Hadwiger and Nelson) is to find the minimal number of colors one needs to color all points in the Euclidean plane so that no two points which are distance 1 apart receive the same color. Similar geometric coloring problems can be posed in the context…

Find out more »### ALOP Colloquium with Ingenuin Gasser

On Thursday, December 6, 2018 at 16:00 c.t. Prof. Gasser of Universität Hamburg will present his recent work entitled Modelling, simulation and optimisation of power plants based on renewable energies Abstract: In this seminar we discuss the fluid dynamics of parabolic trough, solar updraft towers, energy towers and osmotic power stations. The main issue is to discuss simple fluid dynamic models which on one hand describe the main features of the mentioned applications and on the other allow…

Find out more »## January 2019

### ALOP Colloquium with Martin Gugat, FAU Erlangen

On Monday, January 28, 2019 at 16:00 c.t. Prof. Dr. Martin Gugat of FAU Erlangen will present his recent work entitled On the limits of boundary stabilizability for networks of strings. Abstract: An example by Bastin and Coron illustrates that theboundary stabilization of 1-d hyperbolic systemswith certain source terms is only possible if the lengthof the space interval is sufficiently small. We show that simlar phenomena also occur fornetworks of vibrating strings that are governedby the wave equation with…

Find out more »## April 2019

### ALOP Colloquium with Florian Jarre, Universität Düsseldorf

On Monday, April 29 2019 at 16:00 c.t. Prof. Florian Jarre of Universität Düsseldorf will present his recent work. Stochastic gradient descent und Block coordinate descent -- eine Einführung in die Theorie und die praktische Anwendung Der Vortrag befasst sich mit extrem hoch-dimensionalen speziell strukturierten Minimierungsproblemen, für die selbst die Auswertung eines einzelnen Funktionswertes oft so viel Rechenzeit beansprucht, dass neue iterative Verfahren zum Einsatz kommen, bei denen die einzelnen Iterationen billiger sind als eine Funktionsauswertung. Natürlich kann man…

Find out more »## May 2019

### ALOP Colloquium with Christian Meyer, TU Dortmund

On Monday, May 6 2019 at 16:00 c.t. Prof. Dr. Christian Meyer of TU Dortmund will present his recent work entitled Optimal control of a non-smooth semi-linear elliptic equation The presentation will take place in HS 9. Please join us for coffee at 15:45 in E10.

Find out more »## June 2019

### ALOP Colloquium with Barbara Kaltenbacher, Universität Klagenfurt

On Monday, June 17 2019 at 16:00 c.t. Prof. Dipl.-Ing. Dr. Barbara Kaltenbacher of AAU Klagenfurt will present her recent work entitled Optimization based formulation and regularization of inverse problems Abstract: The conventional way of formulating inverse problems such as identification of a (possibly infinite dimensional) parameter, is via some forward operator, which is the concatenation of the observation operator with the parameter-to-state-map for the underlying model. Recently, all-at-once formulations have been considered as an alternative to this reduced…

Find out more »## July 2019

### ALOP Colloquium with Christopher Hojny, TU Darmstadt

On Monday, July 1 2019 at 16:00 c.t. Dr. Christopher Hojny, TU Darmstadt will present his recent work entitled Symmetry Handling in Binary Programs - Combining Symretopes and Orbital Fixing Abstract: Branch-and-bound is an established method to solve binary programs with thousands of variables in adequate time. If symmetries are present, however, even small instances may be hard to solve, because symmetric parts of the branch-and-bound tree are inspected repeatedly without providing new information. A standard way to handle symmetries…

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