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BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200129T140000
DTEND;TZID=Europe/Berlin:20200218T171500
DTSTAMP:20191017T124620Z
CREATED:20191017T123456Z
LAST-MODIFIED:20191017T124620Z
UID:3138-1580306400-1582046100@alop.uni-trier.de
SUMMARY:Short course on the Introduction to Mixed-Integer Nonlinear Optimization
DESCRIPTION:Prof. Dr. Martin Schmidt\, a Principal Investigator of the Research Training Group on Algorithmic Optimization\, is offering a short course on the Introduction to Mixed-Integer Nonlinear Optimization. \nThe course will consist of 4 x 2  lectures of 90 minutes each on the following dates and times: \nWednesday\,                     21 January 2020                     14:00 – 17:15                                              HS 10 \nWednesday\,                      5 February 2020                    14:00 – 17:15                                              HS 10 \nWednesday\,                     12 February 2020                   14:00 – 17:15                                              HS 10 \nTuesday\,                           18 February 2020                   14:00 – 17:15                                              HS 10 \nCourse Abstract: \nMixed-integer nonlinear optimization problems (MINLPs) are of great importance in practice because they allow for two crucial modeling aspects. First\, using integer variables makes it possible to model decision-making. Second\, accurate modeling of real-world phenomena often leads to nonlinearities like in physics or in models of economies of scale. However\, the combination of integer variables and nonlinearities also makes these problems extremely hard to solve for large-scale instances of real-world applications. \n  \nIn this compact course\, we introduce the class of convex and nonconvex MINLPs\, discuss some MINLP-specific modeling tricks\, and study the basic algorithms for solving MINLPs. \nFor a printout of this information\, please click here. \nCourse outline: \nDay 1: Introduction to the problem class of MINLPs\n* Definition of problem class\n* Convex vs. nonconvex MINLP\n* Modeling examples\n* Modeling techniques\n* Good and bad formulations\n* General algorithmic techniques for solving MINLPs \nDay 2: Algorithmic techniques\n* Nonlinear branch-and-bound\n* Kelley’s cutting plane method\n* Outer approximation\n* LP-/NLP-based branch-and-bound \nDay 3: Getting rid of what makes the problem hard\n* MIP-based solution techniques\n* NLP-based solution techniques \nDay 4: Nonconvex MINLPs and Software\n* Under- and overestimators\n* expression trees\n* Generic relaxation strategies for nonconvex MINLPs\n* Spatial branch-and-bound\n* Modeling software (GAMS\, AMPL\, Pyomo)\n* Solvers \n 
URL:https://alop.uni-trier.de/event/short-course-on-the-introduction-to-mixed-integer-nonlinear-optimization/
CATEGORIES:Short Course
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200206T130000
DTEND;TZID=Europe/Berlin:20200206T160000
DTSTAMP:20191114T122557Z
CREATED:20191114T122557Z
LAST-MODIFIED:20191114T122557Z
UID:3227-1580994000-1581004800@alop.uni-trier.de
SUMMARY:Mathematical Writing Course with Mirjam Duer
DESCRIPTION:Prof. Dr. Mirjam Dür with Augsburg University will teach a Mathematical Writing Course on Thursday\, February 6\, 2020 from 1 to 4 pm in Room E 10.
URL:https://alop.uni-trier.de/event/mathematical-writing-course-with-mirjam-duer/
LOCATION:Trier University E Building\, Universitätsring 15\, Trier\, 54296\, Germany
CATEGORIES:Workshop
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200210T160000
DTEND;TZID=Europe/Berlin:20200210T180000
DTSTAMP:20200203T155305Z
CREATED:20200113T160241Z
LAST-MODIFIED:20200203T155305Z
UID:3315-1581350400-1581357600@alop.uni-trier.de
SUMMARY:CANCELLED - ALOP Colloquium with Shengfeng Zhu
DESCRIPTION:CANCELLED DUE TO THE CURRENT TRAVEL RESTRICTIONS IN CHINA\nThis presentation will be rescheduled at a later time. \nOn Monday\, February 10 2020 at 16:00 c.t.  Dr. Shengfeng Zhu of East China Normal University  will present his recent work \nentitled Finite element approximations of shape gradients with applications in shape optimization  \nAbstract: \nShape optimization has many practical applications in science and engineering. Boundary type Eulerian derivative has been widely used in shape gradient algorithms. The distributed Eulerian derivative is seldom noticed. For model problems of eigenvalue optimization and shape design in flows\, we present two types of discrete finite element schemes for shape gradients contained in distributed and boundary types of Eulerian derivatives. Our a prior error estimates show that the discrete shape gradient associated with the distributed Eulerian derivative on a fixed domain has higher convergence rate and better accuracy. Furthermore\, we report numerical evidence that the distributed shape gradient algorithm can have better numerical performance during deformations.  \n\n  \nThe presentation will take place in HS 9. \nPlease join us for coffee at 15:45 in E10. \nCANCELLED DUE TO THE CURRENT TRAVEL RESTRICTIONS IN CHINA
URL:https://alop.uni-trier.de/event/alop-colloquium-with-dr-shengfeng-zhu/
LOCATION:Trier University E Building\, Universitätsring 15\, Trier\, 54296\, Germany
CATEGORIES:Colloquium
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200224T160000
DTEND;TZID=Europe/Berlin:20200224T180000
DTSTAMP:20191108T111752Z
CREATED:20191016T115717Z
LAST-MODIFIED:20191108T111752Z
UID:3122-1582560000-1582567200@alop.uni-trier.de
SUMMARY:ALOP Colloquium with Marianna de Santis
DESCRIPTION:On Monday\, February 24 2020 at 16:00 c.t.  Dr. Marianna de Santis\, Università de Roma\, DIAG  will present her recent work \nentitled Branch-and-bound Algorithms for structured Mixed Integer Nonlinear Programming Problems \nAbstract: \nMixed Integer Nonlinear Programming (MINLP) is the area of optimization  that addresses nonlinear problems with continuous and integer variables.  MINLP has proven to be a powerful tool for modeling and it combines challenges from both combinatorial and nonlinear optimization. \nIn this talk\, we deal with the computation of dual bounds for different classes of structured MINLPs. In particular\, we will focus on problems having quadratic objective function. \nThe branch-and-bound algorithms presented generalize the approach for unconstrained convex quadratic integer programming proposed by Buchheim\, Caprara and Lodi [Math.Progr.\, 135\, pp.369-395 (2012)] to the presence of linear constraints and nonconvex objective function. The main feature of the latter approach consists of a sophisticated preprocessing phase\, leading to a fast enumeration on the branch-and-bound nodes. \nExperimental results on randomly generated instances show that the approach significantly outperforms the MIQP solver of CPLEX12.6 for instances with a small number of constraints. Hints on how to extend the key ideas to more general contexts will be given. \n  \nThe presentation will take place in HS 9. \nPlease join us for coffee at 15:45 in E10.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-marianna-de-santis/
LOCATION:Trier University E Building\, Universitätsring 15\, Trier\, 54296\, Germany
CATEGORIES:Colloquium
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200303T160000
DTEND;TZID=Europe/Berlin:20200303T180000
DTSTAMP:20200207T084612Z
CREATED:20200205T095641Z
LAST-MODIFIED:20200207T084612Z
UID:3341-1583251200-1583258400@alop.uni-trier.de
SUMMARY:ALOP Colloquium with Hanno Gottschalk
DESCRIPTION:On Tuesday\, March 3 2020 at 16:00 c.t.  Prof. Dr. Hanno Gottschalk  \, Bergische Universität Wuppertal  will present his recent work. entitled \nFalse Positives and False Negatives in Semantic Segmentation: Toward the assurance of the perception with deep CNN in atonomous driving \nAbstract: \nThe application of machine learning technology in safety relevant environments poses several challenges regarding their reliability. This especially applies to modern deep learning architectures\, which pretty much resemble a black box. In this talk\, measures of uncertainty from basic classification algorithms to current fully convolutional networks for semantic segmentation are discussed. We present known and new uncertainty measures and use them in meta classification: An algorithmic decision\, if a prediction by the AI is correct of not\, without access to the ground truth data. For the case of semantic segmentation\, we use this for the instance based detection of false positives. Techniques for the detection of false negatives are discussed as well. Both techniques can be fused for a more reliable detection of underrepresented classes\, like pedestrians in street scenes.  \n  \nThe presentation will take place in HS 9. \nPlease join us for coffee at 15:45 in E10.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-hanno-gottschalk/
LOCATION:Trier University E Building\, Universitätsring 15\, Trier\, 54296\, Germany
CATEGORIES:Colloquium
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200504T100000
DTEND;TZID=Europe/Berlin:20200516T120000
DTSTAMP:20200205T102246Z
CREATED:20200205T102002Z
LAST-MODIFIED:20200205T102246Z
UID:3345-1588586400-1589630400@alop.uni-trier.de
SUMMARY:Short Course on Computational Statistics
DESCRIPTION:PD Dr. Jan Pablo Burgard\, a Principal Investigator with the Research Training Group on Algorithmic Optimization\, is offering a short course on Computational Statistics during the summer semester 2020. \nThe course will consist of several lectures of 90 minutes each. The exact dates and times will be announced shortly. \n  \nCourse Abstract to follow.
URL:https://alop.uni-trier.de/event/short-course-on-computational-statistics/
LOCATION:Trier University E Building\, Universitätsring 15\, Trier\, 54296\, Germany
CATEGORIES:Short Course
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200518T100000
DTEND;TZID=Europe/Berlin:20200528T120000
DTSTAMP:20200205T102052Z
CREATED:20200205T100739Z
LAST-MODIFIED:20200205T102052Z
UID:3343-1589796000-1590667200@alop.uni-trier.de
SUMMARY:Short Course on Optimization on Manifolds
DESCRIPTION:Prof. Dr. Volker Schulz\, Speaker of the Research Training Group on Algorithmic Optimization\, is offering a short course on the Optimization on Manifolds during the summer semester 2020. \nThe course will consist of several lectures of 90 minutes each. The exact dates and times will be announced shortly. \n  \nCourse Abstract to follow.
URL:https://alop.uni-trier.de/event/short-course-on-optimization-on-manifolds/
LOCATION:Trier University E Building\, Universitätsring 15\, Trier\, 54296\, Germany
CATEGORIES:Short Course
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200520T121500
DTEND;TZID=Europe/Berlin:20200520T130000
DTSTAMP:20200527T094633Z
CREATED:20200426T110144Z
LAST-MODIFIED:20200527T094633Z
UID:3700-1589976900-1589979600@alop.uni-trier.de
SUMMARY:Lukas Mich to speak during the research seminar
DESCRIPTION:ALOP member Lukas Mich will speak during the research seminar on  May 20\, 2020 at 12:15 on the topic \n“Solving High-dimensional Stochastic Optimal Control Problems using Neural Networks“. \n \nPlease join as via ZOOM at 12:15 by clicking this link \n  \n 
URL:https://alop.uni-trier.de/event/lukas-mich-to-speak-during-the-research-seminar/
CATEGORIES:Presentation
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200603T121500
DTEND;TZID=Europe/Berlin:20200603T130000
DTSTAMP:20200527T094612Z
CREATED:20200526T110022Z
LAST-MODIFIED:20200527T094612Z
UID:3698-1591186500-1591189200@alop.uni-trier.de
SUMMARY:Michael Vu to speak during the research seminar
DESCRIPTION:ALOP member Michael Vu will speak during the research seminar on June 3\, 2020 at 12:15 about his work. \nPlease join as via ZOOM at 12:15 by clicking this link \n  \n 
URL:https://alop.uni-trier.de/event/michael-vu-to-speak-during-the-research-seminar/
CATEGORIES:Presentation
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200615T170000
DTEND;TZID=Europe/Berlin:20200615T180000
DTSTAMP:20200527T102733Z
CREATED:20200526T085037Z
LAST-MODIFIED:20200527T102733Z
UID:3683-1592240400-1592244000@alop.uni-trier.de
SUMMARY:ALOP Colloquium with Prof. Andrés Gómez
DESCRIPTION:Assistant Professor Andrés Gómez of Daniel J. Epstein Department of Industrial and Systems Engineering\, University of Southern California\, will speak at our colloquium on June 15\, 2020 at 5 pm about his research via ZOOM. \nTitle: Sparse learning via mixed-integer optimization. \n  \nAbstract: This talk addresses inference problems in which sparsity plays a fundamental role. Sparse statistical models are interpretable by design and often have improved out-of-sample performance than dense models\, but learning a sparse model model from data often results in a combinatorial optimization problems. Unfortunately\, off-the-shelf mixed-integer optimization software struggle with the resulting problems\, resulting in prohibitive solution times even in small instances. We discuss techniques to improve the performance\, often related to the convexification of the underlying combinatorial problems. \nFor more details regarding the Zoom link\, please refer back to this page.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-andres-gomez/
CATEGORIES:Colloquium
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200617T161500
DTEND;TZID=Europe/Berlin:20200617T171500
DTSTAMP:20200615T063405Z
CREATED:20200610T115141Z
LAST-MODIFIED:20200615T063405Z
UID:3748-1592410500-1592414100@alop.uni-trier.de
SUMMARY:Mercator Fellow Matthias Heinkenschloss scheduled to lecture via ZOOM
DESCRIPTION:Research Training Group ALOP’s Mercator Fellow\, Prof. Dr. Matthias Heinkenschloss of Rice University\, will present a special lecture on Wednesday\, June 17\, 2020 at  16:15 local time via ZOOM. You may enter the waiting area beginning at 16:00. The presentation will take appr. 1 hour. \nProf. Heinkenschloss will speak on the topic of  \n  \nNumerical Solution of Risk-Averse PDE-Constrained Optimization Problems\n \nAbstract\nThis talk gives a unified presentation of several recent optimization approaches for solving risk-averse partial differential equation constrained optimization problems and addresses a numerical issue that arises in (semismooth) Newton methods used to solve subproblems in each of these approaches. Risk-averse optimization problems arise\, for example\, in engineering applications when one seeks to maximize the performance of\, or minimize the costs of a system under uncertainty. Whereas risk-neutral formulations optimize the average costs or performance\, risk-averse formulations penalize high-cost\, rare-events\, which yield excessively high costs or low performance. Risk-averse objectives like the Conditional Value-at-Risk (CVaR) are notoriously expensive to optimize due to their non-smooth nature and the inherent expense in sampling rare-events.\nThis talk focusses on the CVaR risk measure and studies recent optimization approaches which either directly smooth the CVaR or are based on a reformulation as a smooth inequality constrained problem\, such as log-barrier or augmented Lagrangian approaches. It is shown that all considered approaches solve the CVaR optimization problem by solving a sequence of smoothed CVaR optimization problems. Furthermore\, a computationally inexpensive modification of (semismooth) Newton methods is introduced that alleviates numerical issues arising from near rank deficient Hessians and inconsistent quadratic models that can arise in the smoothed CVaR subproblems.  \n \nThis talk is based on joint work with Mae Markowski.\n  \nThe ZOOM access link will be forwarded via Email.
URL:https://alop.uni-trier.de/event/mercator-fellow-matthias-heinkenschloss-scheduled-to-lecture-via-zoom/
CATEGORIES:Presentation
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200622T160000
DTEND;TZID=Europe/Berlin:20200622T170000
DTSTAMP:20200508T080832Z
CREATED:20200427T113707Z
LAST-MODIFIED:20200508T080832Z
UID:3606-1592841600-1592845200@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with apl. Prof. Martin Gugat
DESCRIPTION:On Monday\, June 22. 2020 at 16:00 c.t.  apl. Prof. Martin Gugat\,  FAU Erlangen-Nuernberg will present his recent work and speak on the following topic: \n  \nThe finite time turnpike phenomenon for optimal control problems \n\nAbstract: \nOften in dynamic optimal control problems with a long time horizon\, in a large neighburhood of the middle of the time interval the optimal control and the optimal state are very close to the solution of a static control problem that is derived from the dynamic optimal control problems by omitting the information about the initial state and possibly a desired  terminal state. \nWe show that for problems with a non-smooth tracking term in the objective function that is multiplied with a sufficiently large  penalty-parameter in some cases  the optimal state and  the optimal control reach the solution of the static control problem (the so-called turnpike) exactly after finite-time and remain there  during a certain time-interval\, until close to the end of the time interval possibly the state leaves the turnpike. \nThis can be shown in different situations\, for example under exact controllability assumptions or with the assumption of nodal profile exact controllability\, as studied by Tatsien Li and his group. \n\n__________________________________________________________________________________________________________________________________________ \nTurnpike ist eine  Bezeichnung für eine Mautstrasse.  Trotz der Kosten (die Maut) werden diese Strassen oft benutzt. Da die Fahrerinnen ihren Nutzen maximieren\, muss das also unter gewissen Voraussetzungen optimal sein. \nBeim Turnpikephänomen geht es darum\, dass die Grundstruktur  einer optimalen Route über die Autobahn (zum Beispiel für einen LKW-Eiltransport von Trier nach Koblenz) für einen Startpunkt in einer Umgebung von Trier\nund einen Endpunkt in einer gewissen Umgebung von Koblenz weder vom Startpunkt noch vom Endpunkt abhängt. Die optimale Route führt zu einer Autobahnauffahrt\, bleibt dann eine gewisse Strecke auf der Autobahn und\nfährt dann am Ende wieder ab. \nEine ähnliche Struktur tritt auch bei der Lösung von dynamischen Optimalsteuerungsproblemen mit partiellen Differentialgleichungen auf\, die zum Beispiel als Modell des Betriebs von Gaspipelinenetzen verwended werden können. \n  \nThe presentation will take place remotely via Zoom. For further details and a link to the presentation please refer to this page.\n \n 
URL:https://alop.uni-trier.de/event/alop-colloquium-with-apl-prof-martin-gugat/
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200624T121500
DTEND;TZID=Europe/Berlin:20200624T130000
DTSTAMP:20200615T142609Z
CREATED:20200526T105906Z
LAST-MODIFIED:20200615T142609Z
UID:3696-1593000900-1593003600@alop.uni-trier.de
SUMMARY:Carina Costa to speak during the research seminar
DESCRIPTION:ALOP member Carina Costa will speak during the research seminar on  June 24\, 2020 at 12:15 on the topic \n““Decomposition Methods for Robustified $k$-Means Clustering Problems: If Less Conservative Does Not Mean Less Bad.“\n \nPlease join as via ZOOM at 12:15 . The link will be distributed via Email. \n 
URL:https://alop.uni-trier.de/event/carina-costa-to-speak-during-the-research-seminar/
CATEGORIES:Presentation
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200629T160000
DTEND;TZID=Europe/Berlin:20200629T180000
DTSTAMP:20200623T063900Z
CREATED:20200622T094133Z
LAST-MODIFIED:20200623T063900Z
UID:3790-1593446400-1593453600@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Luise Blank
DESCRIPTION:On Monday\, June 29. 2020 at 16:00 c.t.  Prof. Dr. Luise Blank with the Universitaet Regensburg will present her recent work at our colloquium entitled \nOptimization with convex constraints and an application in topology optimization \n\nThis talk focuses on projection type methods for convexly constrained optimization problems. We shortly introduce well known projection methods using the gradient in finite dimensions and summarize known results. Varying the underlying scalar product allows to include second order information to speed up the method. E.g. the projection of the Newton direction leads to a quadratic order of convergence. The method can also be interpreted as solving a sequence of optimization problems where the cost function is quadratically approximated. Results in function spaces are important to obtain methods with iteration numbers independent ot the discretization level. They also indicate which underlying metric shall be used for the projection. E.g. pde constraint problems provide often only differentiability of the cost functional in the L∞ metric. While the generalization to Hilbert spaces is straight forward the extension to Banach spaces is more involved due to the missing scalar product. We present a global convergence result for the variable metric projection type (VMPT-)method\, which allows application to nonreflexive Banach spaces and expand the possible choices of the metric. Moreover\, we give examples which fulfill the requirements on the spaces and the variable metric.\nAs an application we consider a structural topology optimization problem. The model is based on a diffuse interface ansatz using phase field variables. The necessary regularization of the cost functional with the perimeter is substituted by the Ginzburg-Landau energy. We obtain a minimization problem with pde constraints and simplex constraints for the controls. The elimination of the state using the nonlinear control-to-state operator yields a convexly constrained optimization problem\, where we can apply the VMPT-algorithm in L∞ ∩ H1. In the numerical results one can clearly see that choosing an appropriate inner product\, namely H1\, leads –in contrast to L2– to mesh independency of the iteration numbers. Including additionally second order information speeds up the method drastically. \nThe presentation will take place remotely via Zoom.  \nIf you wish to receive a link and invitation to this presentation\, please send an email to shawATuni-trier.de
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-dr-luise-blank/
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200713T160000
DTEND;TZID=Europe/Berlin:20200713T170000
DTSTAMP:20200630T101304Z
CREATED:20200615T085803Z
LAST-MODIFIED:20200630T101304Z
UID:3761-1594656000-1594659600@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Julia Gruebel\, M.Sc.\, FAU Erlangen-Nuernberg
DESCRIPTION:On Monday\, July 13. 2020 at 16:00 c.t.  Julia Gruebel\, FAU Erlangen-Nuernberg will present her recent work via a ZOOM presentation.  \nTitel: On Electricity Market Equilibria with Storage: Modeling\, Uniqueness\, and a Distributed ADMM\n Abstract: This talk focuses on spot-market trading of electricity including storage operators as additional agents besides producers and consumers. Storage devices allow for shifting produced electricity from one time period to a later one. Due to this\, multiple market equilibria may occur even if classical uniqueness assumptions for the case without storage systems are satisfied. For models containing storage operators\, we derive sufficient conditions that ensure uniqueness of generation and demand. We also prove uniqueness of the market equilibrium for the special case of a single storage operator. Nevertheless\, in case of multiple storage operators\, uniqueness fails to hold in general\, which we show by illustrative examples. We conclude the theoretical discussion with a general ex-post condition for proving the uniqueness of a given solution. In contrast to classical settings without storage systems\, the computation of market equilibria is much more challenging since storage operations couple all trading events over time. For this reason\, we propose a tailored parallel and distributed alternating direction method of multipliers (ADMM) for efficiently computing spot-market equilibria over long time horizons. We first analyze the parallel performance of the method itself. Finally\, we show that the parallel ADMM clearly outperforms solving the respective problems directly and that it is capable of solving instances with more than 42 million variables in less than 13 minutes. \n  \nThe ZOOM access link will be shared via email prior to the event.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-julia-gruebel/
CATEGORIES:Colloquium
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200715T121500
DTEND;TZID=Europe/Berlin:20200715T131500
DTSTAMP:20200615T143005Z
CREATED:20200615T143005Z
LAST-MODIFIED:20200615T143005Z
UID:3768-1594815300-1594818900@alop.uni-trier.de
SUMMARY:Daniel Hoffmann to speak during Research Seminar
DESCRIPTION:ALOP member Daniel Hoffmann will speak during the research seminar on July 15\, 2020 on the topic \n“Branching Diffusions with Jumps and Valuation with Systemic Counterparts”\n \nPlease join as via ZOOM at 12:15 . The link will be distributed via Email.
URL:https://alop.uni-trier.de/event/daniel-hoffmann-to-speak-during-research-seminar/
CATEGORIES:Presentation
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200720T160000
DTEND;TZID=Europe/Berlin:20200720T180000
DTSTAMP:20200702T125404Z
CREATED:20200625T140724Z
LAST-MODIFIED:20200702T125404Z
UID:3802-1595260800-1595268000@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Mathieu Besançon
DESCRIPTION:On Monday\, July 20. 2020 at 16:00 c.t.  Mathieu Besançon of INRIA will present his recent work at our colloquium: \nNear-optimality robustness in bilevel optimization\n \nBilevel optimization studies problems where the optimal response to a second mathematical optimization problem is integrated in the constraints. We introduce near-optimal robustness for bilevel problems\, protecting the upper-level decision-maker from bounded rationality at the lower level. This model finds a corresponding and intuitive interpretation in various situations cast as bilevel optimization problems. We develop a duality-based solution method for cases where the lower level is convex\, leveraging the methodology from robust and bilevel literature.\nThe presentation will take place remotely via Zoom.  \nIf you wish to receive a link and invitation to this presentation\, please send an email to shawATuni-trier.de
URL:https://alop.uni-trier.de/event/alop-colloquium-with-mathieu-besancon/
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;VALUE=DATE:20201012
DTEND;VALUE=DATE:20201015
DTSTAMP:20201026T163701Z
CREATED:20200210T073741Z
LAST-MODIFIED:20201026T163701Z
UID:3347-1602460800-1602719999@alop.uni-trier.de
SUMMARY:Autumn School on Bilevel Optimization
DESCRIPTION:The Research Training Group on Algorithmic Optimization proudly announces its fifth annual \nAutumn School scheduled to take place from October 12 – 14\, 2020.  \nThis year’s Autumn School will take place in a digital setting (via ZOOM).\n \n  \nConfirmed speakers are: \nMartine Labbé\, Université Libre de Bruxelles \nIvana Ljubic\, Essec Business School \nDidier Aussel\, University of Perpignan \n  \nOrganizers:  \n \nMarina Leal Palazon\, Universidad de Valencia \nMartin Schmidt\, Trier University \n  \nThe workshop is scheduled to begin on  Monday\, October 12\, 2020. \nPlease download the schedule of the sessions here.   \n\nFor a list of Elevator Pitches scheduled on Monday\, click here\nFor a list of Elevator Pitches scheduled on Tuesday\, click here\n\nHere are the slides of Martine Labbé’s presentation on October 12\, 2020. \nHere are the slides of Ivana Ljubic’s presentation on October 13\, 2020. \nHere are the slides of Didier Aussel’s presentation on October 14\, 2020. \nElevator Pitches by the participants: \nÁlvaro Porras Cabrera \nAzucena Orellana\nDavid Salas\nDavid Villacis\nDorothee Henke\nKai Hoppmann Baum\nMaria Asuncion Jimenez Cordero\nMartina Cerulli\nMiguel Angel Muñoz Diaz\nPaula Castro\nPradeep Kumar Sharma\nShraddha Ghatkar\nPamela Alejandra Bustamante Faundez \nVideos of the individual presentation will be shared within the next few weeks. \nPlease refer back to this page for additional information and updates. \n  \n 
URL:https://alop.uni-trier.de/event/autumn-school-on-bilevel-optimization/
CATEGORIES:Autumn School,Conferences
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20201103T080000
DTEND;TZID=Europe/Berlin:20201103T170000
DTSTAMP:20201103T123355Z
CREATED:20201103T123355Z
LAST-MODIFIED:20201103T123355Z
UID:5271-1604390400-1604422800@alop.uni-trier.de
SUMMARY:ALOP member Lena Sembach to speak during Research Seminar
DESCRIPTION:ALOP member Lena Sembach will speak during the research seminar on January 21\, 2021. The topic will be announced soon. \nPlease join as via ZOOM at 12:15 . The link will be distributed via Email.
URL:https://alop.uni-trier.de/event/alop-member-lena-sembach-to-speak-during-research-seminar/
CATEGORIES:Presentation
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20201109T160000
DTEND;TZID=Europe/Berlin:20201109T180000
DTSTAMP:20201008T063928Z
CREATED:20201008T063327Z
LAST-MODIFIED:20201008T063928Z
UID:5156-1604937600-1604944800@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Volker Mehrmann\, TU Berlin
DESCRIPTION:On Monday\, November 9. 2020 at 16:00 c.t. Prof. Dr. Volker Mehrmann\, TU Berlin will present his recent work at our colloquium entitled \nHierarchical energy based modeling\, simulation and control  of multi-physics systems.  \nAbstract:   The next level of digitization will create digital twins of every product or process. To do this in a mathematical rigorous and risk and error controlled way\, a new modeling\, simulation and optimization paradigm is needed. While automated modularized modeling is common in some domains like circuit design or multi-body dynamics\, it becomes increasingly challenging  when systems or numerical solvers from different physical domains are coupled\, due to largely different scales or modeling accuracy\, and very different software technologies. \nA recent system theoretic approach to address these challenges is the use of network based energy based modeling via constrained port-Hamiltonian (pH) systems\, where the coupling is done in a physically meaningful way via energy variables. Furthermore\, for each subsystem a whole model hierarchy can be employed  ranging from very fine grane models to highly reduced surrogate  models arising from model reduction or data based modeling. The model hierarchy allows adaptivity not only in the discretization but also in the model selection. \nWe will present an overview over the  hierarchical pH modeling approach and illustrate the advantages: \nVery robust models which are close to the real physics\,  invariance of the structure under Galerkin projection discretization or model reduction as well as state and time dependent coordinate changes. \nThe results are illustrated with numerical results at the hand of several real world applications. \nThe event is a virtual event via ZOOM. The link will be distributed via email. \n\n \n 
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-dr-volker-mehrmann-tu-berlin/
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20201123T160000
DTEND;TZID=Europe/Berlin:20201123T180000
DTSTAMP:20201013T082134Z
CREATED:20201013T082059Z
LAST-MODIFIED:20201013T082134Z
UID:5188-1606147200-1606154400@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Rakesh Vohra\, University of Pennsylvania
DESCRIPTION:On Monday\, November 23\, 2020 at 16:00  Prof. Dr. Rakesh Vohra\, University of Pennsylvania will present his recent work at our colloquium entitled \n  \nLinear Programming and Prophet Inequalities   \nProphet inequalities bound the expected reward that can be obtained in a class of stopping problems by the optimal reward of the corresponding off-line problem. We use linear programming techniques to obtain prophet inequalities for a class of stopping problems associated with selecting a point in a polyhedron. One application is to `computational sprinting’\,  in which a chip temporarily exceeds its sustainable thermal power budget to provide instantaneous throughput\, after which the chip must return to nominal operation to cool down. We also illustrate the usefulness of the approach by giving some new and simple derivations of existing results. \nThis is based on joint work with Markos Epitropu. \nThis presentation will take place via ZOOM. A link will be e-mailed prior to the event.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-dr-rakesh-vohra-university-of-pennsylvania/
CATEGORIES:Colloquium
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20201125T121500
DTEND;TZID=Europe/Berlin:20201125T131500
DTSTAMP:20201028T114716Z
CREATED:20201028T113622Z
LAST-MODIFIED:20201028T114716Z
UID:5252-1606306500-1606310100@alop.uni-trier.de
SUMMARY:ALOP Member Max Spaeth to speak during Research Seminar
DESCRIPTION:ALOP member Max Späth will speak during the research seminar on November 25\, 2020. The topic will be announced shortly. \nPlease join as via ZOOM at 12:15 . The link will be distributed via Email.
URL:https://alop.uni-trier.de/event/max-spaeth-to-speak-during-research-seminar/
CATEGORIES:Presentation
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20201207T160000
DTEND;TZID=Europe/Berlin:20201207T180000
DTSTAMP:20201128T141102Z
CREATED:20201103T174017Z
LAST-MODIFIED:20201128T141102Z
UID:5273-1607356800-1607364000@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Dr. Christina Schenk\, Basque Center for Applied Mathematics
DESCRIPTION:On Monday\, December 7\,  2020 at 16:00 c.t. Dr. Christina Schenk will present her recent work titled “Population Balance Modeling\, Simulation and Optimization: From Wine Fermentation to Polymerization” at our colloquium.  \nAbstract: \nThe continuous increase of energy consumption and pollution by carbon dioxide emissions worldwide requires\nimprovements in terms of energy efficiency and advanced materials. Within the scope of this talk we look at\ndifferent aspects regarding mathematical modeling\, simulation and optimization for several industrial applications.\nThe proposed mathematical advances tackle the dynamical processes\, and modeling such processes is\ncrucial for many applications. We focus in particular on the process of wine fermentation driven by the yeast cell\ngrowth dynamics and the polymerization of composite (multi-phase) polymer particles which strongly depends\non the evolution of the particle morphology. For these applications we propose models based on population\nbalance equations and derive numerical solution strategies that are adjusted to the specific model properties.\nThese solution approaches reach from finite volume based schemes to the generalized method of characteristics.\nThe arising challenges associated with these types of problems are addressed and handled by newly developed\ntechniques\, such as Optimal Scaling with Constraints. The investigations are underlined with selected analytical\nstudies. The significance of the proposed methodologies is highlighted and verified by numerical results.\n(This is joint work with: S. Rusconi (BCAM)\, E. Akhmatskaya (BCAM\, Ikerbasque\, Berkeley Lab)\, V. Schulz\n(Trier University)\, D. Sokolovski (UPV/EHU\, Ikerbasque)\, A. Zarnescu (BCAM\, Ikerbasque)). \nThe event is a virtual event via ZOOM. The link will be distributed via email. \n 
URL:https://alop.uni-trier.de/event/alop-colloquium-with-dr-christina-schenk-basque-center-for-applied-mathematics/
CATEGORIES:Colloquium
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20201214T160000
DTEND;TZID=Europe/Berlin:20201214T180000
DTSTAMP:20201207T162808Z
CREATED:20201008T115646Z
LAST-MODIFIED:20201207T162808Z
UID:5163-1607961600-1607968800@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Falk Hante\, HU Berlin
DESCRIPTION:On Monday\, December 14\, 2020 at 16:00\, Prof. Dr. Falk Hante\, Humbold Universität zu Berlin will present his recent work at our colloquium. \n  \nTitle: Sequential action control for stabilization of PDE-dynamical systems \nWe present sequential action control as a framework suitable for control and stabilization of PDE-dynamical problems. As a variant of a moving horizon method\, but in contrast to classical model predictive control approaches\, the control synthesis does not require to compute solutions of dynamic optimization problems. Moreover\, the control principle can be easily extended to piecewise linear switched systems and other heterogenuous optimal control problems being motivated\, for example\, by gas network operation. We use Riccati theory for the qualitative analysis of the method and present results prototypically for the stabilization of an unstable reaction-diffusion process. \nReferences:\n[1] Y. Brodskyi\, F.M. Hante\, A. Seidel: Stabilization of Partial Differential Equations by Sequential Action Control. TRR154 Preprint 271\, 2019. \n  \nThis presentation will take place via ZOOM. A link will be e-mailed prior to the event.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-dr-falk-hante-hu-berlin/
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20201216T121500
DTEND;TZID=Europe/Berlin:20201216T131500
DTSTAMP:20201028T114817Z
CREATED:20201028T114339Z
LAST-MODIFIED:20201028T114817Z
UID:5260-1608120900-1608124500@alop.uni-trier.de
SUMMARY:ALOP Member Anke-Julia Gebhardt to speak during Research Seminar
DESCRIPTION:ALOP member Anke-Julia Gebhardt will speak during the research seminar on December 16\, 2020. The topic will be announced shortly. \nPlease join as via ZOOM at 12:15 . The link will be distributed via Email.
URL:https://alop.uni-trier.de/event/alop-member-anke-julia-gebhardt-to-speak-during-research-seminar/
CATEGORIES:Presentation
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20210125T160000
DTEND;TZID=Europe/Berlin:20210125T180000
DTSTAMP:20201013T043841Z
CREATED:20201013T042122Z
LAST-MODIFIED:20201013T043841Z
UID:5180-1611590400-1611597600@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Steven Gabriel\, University of Maryland
DESCRIPTION:On Monday\, January 25\, 2021 at 16:00 c.t. Prof. Dr. Steven Gabriel of the University of Maryland \, Baltimore will present his recent work at our colloquium entitled \n  \nA parametric programming approach to bilevel optimisation with lower-level variables in the upper level \nThis paper examines linearly constrained bilevel programming problems in which the upper-level\nobjective function depends on both the lower-level primal and dual optimal solutions. We parametrize\nthe lower-level solutions and thereby the upper-level objective function by the upper-level variables\nand argue that it may be non-convex and even discontinuous. However\, when the upper-level\nobjective is affine in the lower-level primal optimal solution\, the parametric function is piece-wise linear.\nWe show how this property facilitates the application of parametric programming and demonstrate how\nthe approach allows for decomposition of a separable lower-level problem. When the upper-level\nobjective is bilinear in the lower-level primal and dual optimal solutions\, we also provide an exact\nlinearisation method that reduces the bilevel problem to a single-level mixed-integer linear programme\n(MILP). We assess the performance of the parametric programming approach on two case studies of\nstrategic investment in electricity markets and benchmark against state-of-the-art MILP and non-linear\nsolution methods for bilevel optimisation problems. Preliminary results indicate substantial\ncomputational advantages over several standard solvers\, especially when the lower-level problem\nseparates into a large number of subproblems. Furthermore\, we show that the parametric\nprogramming approach succeeds in solving problems to global optimality for which standard methods\ncan fail. \nFor further information\, please refer to this article: Henrik C. Bylling\, Steven A. Gabriel & Trine K. Boomsma (2020) A parametric programming approach to bilevel optimisation with lower-level variables in the upper level\, Journal of the Operational Research Society\, 71:5\, 846-865\, DOI: 10.1080/01605682.2019.1590132\nTo link to this article: https://doi.org/10.1080/01605682.2019.1590132 \n  \nThis presentation will take place via ZOOM. A link will be e-mailed prior to the event.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-steven-gabriel-university-of-maryland/
CATEGORIES:Colloquium
ORGANIZER;CN="RTG ALOP at Trier University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20210407T121500
DTEND;TZID=Europe/Berlin:20210407T131500
DTSTAMP:20210308T100955Z
CREATED:20210308T100955Z
LAST-MODIFIED:20210308T100955Z
UID:5360-1617797700-1617801300@alop.uni-trier.de
SUMMARY:ALOP member Marc Harmening to speak during Research Seminar
DESCRIPTION:ALOP member Marc Harmening will speak about his work during the research seminar on April 7\, 2020. The topic will be announced shortly. \nPlease join as via ZOOM at 12:15 . The link will be distributed via Email.
URL:https://alop.uni-trier.de/event/alop-member-marc-harmening-to-speak-during-research-seminar/
CATEGORIES:Presentation
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20210419T160000
DTEND;TZID=Europe/Berlin:20210419T170000
DTSTAMP:20210308T095421Z
CREATED:20210308T095421Z
LAST-MODIFIED:20210308T095421Z
UID:5356-1618848000-1618851600@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Tobias Harks\, Augsburg University
DESCRIPTION:On Monday\, April 19\, 2021 at 16:00 c.t. Prof. Dr. Tobias Harks of Augsburg University will present his recent work at our colloquium entitled \n  \nPricing in Resource Allocation Games \nWe consider a basic resource allocation game\, where the players’ strategy spaces are subsets of R^m and cost/utility functions are parameterized by some common vector u \in∈ R^m and\, otherwise\, only depend on the own strategy choice. A strategy of a player can be interpreted as a vector of resource consumption and a joint strategy profile naturally leads to an aggregate consumption vector. Resources can be priced\, that is\, the game is augmented by a price vector \lambda\inλR^m_+ and players have quasi-linear overall costs/utilities meaning that in addition to the original costs/utilities\, a player needs to pay the corresponding price per consumed unit. \n  \nWe investigate the following question: for which aggregated consumption vectors u can we find prices \lambdaλ that induce an equilibrium realizing the targeted consumption profile? For answering this question\, we revisit a well-known duality-based framework and derive several characterizations of the existence of such u and \lambda. We show that the characterization can help to unify parts of several largely independent streams in the literature – tolls in transportation systems\, Walrasian market equilibria\, trading networks\, energy networks and congestion control in communication networks. Besides reproving existing results we establish novel existence results by using methods from polyhedral combinatorics\, global optimization and discrete convexity. \nThe presentation will take place via Zoom. A link will be email prior to the event.\n \nIf you wish to receive a link and invitation to this presentation\, please send an email to shawATuni-trier.de
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-dr-tobias-harks-augsburg-university/
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20210426T160000
DTEND;TZID=Europe/Berlin:20210426T170000
DTSTAMP:20210412T160553Z
CREATED:20210412T160553Z
LAST-MODIFIED:20210412T160553Z
UID:5500-1619452800-1619456400@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Dr. Ritesh Kumar Dubey of SRM University Chennai
DESCRIPTION:On Monday\, April 26\, 2021 at 16:00 c.t.  Dr. Ritesh Kumar Dubey of SRM University Chennai will present his recent work at our colloquium.  \n  \nTitle of the Talk: On numerical diffusion for entropy stable shock capturing schemes for hyperbolic conservation laws \nOne of the fundamental problems associated with the solution of hyperbolic conservation laws is the presence of inevitable discontinuities in it. This poses various challenges for the numerical approximation of such admissible solutions which eventually demand to construct numerical schemes which can yield physically correct non-oscillatory and crisp resolution of these discontinuities in the solution. To address this\, we use entropy stability framework and construct high order non-oscillatory entropy stable fluxes by devising suitable numerical diffusion using three different approaches (i) Non-linear stability (ii) Deep neural network and (iii) Optimization . This talk will give a comparative overview of these approaches along with theoretical and numerical results for benchmark test PDE cases. \n  \nThis presentation will take place via ZOOM. A link will be e-mailed prior to the event.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-dr-ritesh-kumar-dubey-of-srm-university-chennai/
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20210503T160000
DTEND;TZID=Europe/Berlin:20210503T170000
DTSTAMP:20210415T120317Z
CREATED:20210415T120317Z
LAST-MODIFIED:20210415T120317Z
UID:5504-1620057600-1620061200@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Bijan Mohammadi\, Montpellier University
DESCRIPTION:On Monday\, May 3\, 2021 at 16:00 c.t. Prof. Dr. Bijan Mohammadi\, Montpellier University\, will present his recent work at our colloquium.  He will speak about \nVariational nearshore dynamics  \nAbstract: \nMinimization principles are used in fluid-structure coupling to model sandy sea beds  evolution.The sandy bed is seen as a structure with low stiffness. We start with a model problem featuring the behavior of the coupling.Then water motion in shallow domains is described by the Saint Venant equations.This coupling bringing the bottom sea changes is based on the assumption that the bed adapts  to the flow in order to minimize some energy quantity togetherwith  minimal  sand transport.  The choice of the functional permits to include different physical quantities one think to play a role in the bottom morphodynamics.Hence\, the approach is also a tool for validating different modelling hypothesis.We also present tentative  direct and reverse uncertainty propagation procedures under the constraint of keeping the computational costcomparable to deterministic simulations.The different ingredients will be illustrated through coastal engineering applications.   \n  \nThe presentation will take place via Zoom. A link will be email prior to the event.\n \nIf you wish to receive a link and invitation to this presentation\, please send an email to shawATuni-trier.de
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-dr-bijan-mohammadi-montpellier-university/
CATEGORIES:Colloquium
END:VEVENT
END:VCALENDAR