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X-WR-CALDESC:Events for Computational Optimisation Group
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DTSTART:20140101T000000
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BEGIN:VEVENT
DTSTART;TZID=UTC:20150303T140000
DTEND;TZID=UTC:20150303T140000
DTSTAMP:20260517T111309
CREATED:20170124T102138Z
LAST-MODIFIED:20170124T102138Z
UID:560-1425391200-1425391200@optimisation.doc.ic.ac.uk
SUMMARY:Seminar: Formal Proofs for Nonlinear Optimization
DESCRIPTION:Title: Formal Proofs for Nonlinear OptimizationSpeaker: Dr. Victor MagronAffiliation: Department of Electrical and Electronic Engineering – Imperial College LondonLocation: Room 217 Huxley BuildingTime: 2:00pm \nAbstract. We present a formally verified global optimization framework. Given a semialgebraic or transcendental function f and a compact semialgebraic domain K\, we use the nonlinear maxplus template approximation algorithm to provide a certified lower bound of f over K. This algorithm allows to bound in a modular way some of the constituents of f by suprema of quadratic forms with a well chosen curvature. Thus\, we reduce the initial goal to a hierarchy of semialgebraic optimization problems\, solved by semidefinite relaxations.  Our implementation tool interleaves semialgebraic approximations with sums of squares witnesses to form certificates. It is interfaced with Coq and thus benefits from the trusted arithmetic available inside the proof assistant. This feature is used to produce\, from the certificates\, both valid underestimators and lower bounds for each approximated constituent. The application range for such a tool is widespread; for instance Hales’ proof of Kepler’s conjecture yields thousands of multivariate transcendental inequalities. We illustrate the performance of our formal framework on some of these inequalities as well as on examples from the global optimization literature.http://cas.ee.ic.ac.uk/people/vmagron/slides/quads.pdf \nAbout the speaker. Victor graduated from Ecole Centrale Paris Engineering School in 2010\, while receiving his MSc from the department of Systems Innovation\, Tokyo University (double diploma). In 2013\, he received his PhD in Computer Science at INRIA Saclay\, Ecole Polytechnique. In 2014\, he was a Postdoc fellow in the MAC team at LAAS in Toulouse\, France. He is currently a Research Assistant at Imperial College for the Circuits and Systems group\, in the department of Electrical and Electronic Engineering.
URL:http://optimisation.doc.ic.ac.uk/event/seminar-formal-proofs-for-nonlinear-optimization/
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BEGIN:VEVENT
DTSTART;TZID=UTC:20150313T150000
DTEND;TZID=UTC:20150313T150000
DTSTAMP:20260517T111309
CREATED:20170124T102137Z
LAST-MODIFIED:20170124T102137Z
UID:559-1426258800-1426258800@optimisation.doc.ic.ac.uk
SUMMARY:Seminar: Supply Chain Optimization - from strategic to operational decision levels
DESCRIPTION:Title: Supply Chain Optimization – from strategic to operational decision levelsSpeaker: Prof. Ana Barbosa-PovoaAffiliation: University of LisbonLocation: CPSE seminar room (C615 Roderic Hill)Time: 3:00pm \nAbstract. Supply Chains are complex systems that involve challenging problems. Such problems require suitable answers so as to guarantee efficiency and responsiveness improvements of the involved systems. When answering to such problems optimization is a possible path to follow aiming at building tools that can help the decision makers on the problems solutions that span from strategic to operational levels. The scientific community has been exploring this pathway but much more is required\, especially due to the outer shell of new emerging problems. The present talk characterizes supply chain decisions and presents some of the work that has been done on the optimization of supply chains detailing specially the work developed by the Operations and Logistics Group of the Centre for Management Studies at Instituto Superior Técnico (IST) in Lisbon. We conclude with a discussion of the tendencies and future challenges in the area. \nAbout the speaker. Ana Barbosa-Póvoa obtained her PhD in Engineering from Imperial College of Science Technology and Medicine. She is currently a Full Professor of Operations and Logistics at the Department of Management and Engineering of Instituto Superior Técnico (IST)\, University of Lisbon\, Portugal where she is the director of the BSc and Master Programs in Engineering and Management. She is a member of the scientific council of IST and of the University Senate. She is also the Vice-president of the Portuguese Association for Operational Research. She has been acting as reviewer to several national and international research scientific boards on research projects. Her research interests are on the supply chain management\, where both forward and reserve structures are included and on the design\, planning and scheduling of flexible systems. Ana has published widely in these areas and supervised several Master and PhD students. Ana in 2008 has received the scientific award of Technical University of Lisbon in the scientific area of Industrial Management.
URL:http://optimisation.doc.ic.ac.uk/event/seminar-supply-chain-optimization-from-strategic-to-operational-decision-levels/
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BEGIN:VEVENT
DTSTART;TZID=UTC:20150317T140000
DTEND;TZID=UTC:20150317T140000
DTSTAMP:20260517T111309
CREATED:20170124T102137Z
LAST-MODIFIED:20170124T102137Z
UID:558-1426600800-1426600800@optimisation.doc.ic.ac.uk
SUMMARY:Seminar: Bifurcation Analysis Using Complete Search Methods
DESCRIPTION:Title: Bifurcation Analysis Using Complete Search Methods Speaker: Dr. Mario Eduardo VillanuevaAffiliation: Centre for Process Systems Engineering at Imperial CollegeLocation: Room 217 Huxley BuildingTime: 2:00pm \nAbstract. When studying a non-linear dynamic system it is important to locate and characterise its equilibrium manifold and its bifurcation regions within a pre-specified computational domain. Except for very few simple cases\, an algebraic characterisation of such manifold is impossible. In this seminar a methodology for locating the equilibrium manifold of non-linear dynamic systems defined by parametric ODEs is presented. This methodology is based on a set-inversion approach which uses state-of-the-art bounding techniques within a complete search algorithm. The efficacy of this approach is illustrated with a challenging non-linear model of an anaerobic digestion process.  \nAbout the speaker. Mario Eduardo Villanueva (MEV) graduated with a BEng in Biochemical Engineering from the Instituto Tecnologico de Veracruz\, Mexico and an MSc in Advanced Chemical Engineering with Process Systems Engineering from Imperial College London. He is currently a PhD student in the Department of Chemical engineering\, under the supervision of Dr. B. Chachuat. His PhD project is concerned with the development of methods and tools for complete search in uncertain dynamic systems.
URL:http://optimisation.doc.ic.ac.uk/event/seminar-bifurcation-analysis-using-complete-search-methods/
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BEGIN:VEVENT
DTSTART;TZID=UTC:20150325T140000
DTEND;TZID=UTC:20150325T140000
DTSTAMP:20260517T111309
CREATED:20170124T102137Z
LAST-MODIFIED:20170124T102137Z
UID:557-1427292000-1427292000@optimisation.doc.ic.ac.uk
SUMMARY:Seminar: The Complexity of Primal-Dual Fixed Point Methods for Ridge Regression
DESCRIPTION:Title: The Complexity of Primal-Dual Fixed Point Methods for Ridge RegressionSpeaker: Prof. Ademir RibeiroAffiliation: Department of Mathematics – Federal University of ParanaLocation: Room 218 Huxley BuildingTime: 2:00pm \nAbstract.  We study the ridge regression (L2 regularized least squares) problem and its dual\, which is also a ridge regression problem. We observe that the optimality conditions can be formulated in several different but equivalent ways\, in the form of a linear system involving a structured matrix depending on a single “stepsize” parameter which we introduce for regularization purposes. This leads to the idea of studying and comparing\, in theory and practice\, the performance of the fixed point method applied to these reformulations. We compute the optimal stepsize parameters and uncover interesting connections between the complexity bounds of the variants of the fixed point scheme we consider. These connections follow from a close link between the spectral properties of the associated matrices. For instance\, some reformulations involve purely imaginary eigenvalues; some involve real eigenvalues and others have all eigenvalues on the complex circle. We show that the deterministic Quartz method—which is a special case of the randomized dual coordinate ascent method with arbitrary sampling recently developed by Qu\, Richtarik and Zhang—can be cast in our framework\, and achieves the best rate in theory and in numerical experiments among the fixed point methods we study. This is joint work with Peter Richtarik (Edinburgh). \nAbout the speaker.  I am an Associate Professor at Department of Mathematics\, Federal University of Parana\, Brazil\, since 1992. I got my undergraduate degree in Mathematics at Federal University of Parana in 1989. In 1993 I finished my MSc in Mathematics\, at IMPA – National Institute for Pure and Applied Mathematics. I got my PhD in Optimization at Federal University of Parana in 2005.  My current research interests are applied mathematics\, continuous optimization\, global and local convergence of algorithms as filter and trust region methods for nonlinear programming and convex optimization\, complexity of direct search methods\, among others. I have been published papers in journals like Applied Mathematics and Computation\, Applied Mathematical Modelling\, Optimization\, Computational Optimization and Applications\, Mathematical Programming and SIAM Journal on Optimization. I have been given talks in some meetings like Optimization Conference (Porto 2007 and Guimarães 2014)\, Brazilian Workshop on Continuous Optimization (Rio de Janeiro 2009 and Florianópolis 2014) and International Symposium on Mathematical Programming (Rio de Janeiro 2006 and Berlin 2012).  I have supervised 2 PhD and 6 MSc students.  In joint work with Elizabeth Wegner Karas\, I also have published a book (in Portuguese)\, called Continuous Optimization: Theoretical and computational aspects. Cengage Learning\, Sao Paulo\, Brazil\, 2013.
URL:http://optimisation.doc.ic.ac.uk/event/seminar-the-complexity-of-primal-dual-fixed-point-methods-for-ridge-regression/
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