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Optimization & Numerical Analysis seminars: Massei
by Federico Poloni 27 Apr '16

27 Apr '16

(This message also serves as a reminder that Claudio Sterle's seminar on "Flow intercepting facility location routing problem: formulation and branch-and-cut solving approach" is scheduled in two days: Friday, 29 April 2016, h. 14:30. ) Speaker: Stefano Massei Affiliation: Scuola Normale Superiore, Pisa Time: Thursday, 5 May 2016, h. 10:00 Place: Sala Seminari Est, Dipartimento di Informatica, Università di Pisa Title: Numerical quasiseparable preservation in matrix functions and in the cyclic reduction Abstract: The quasiseparable structure can be efficiently exploited - in order to speed up computations and storage - by using hierachical representations. This theme has raised much interest in the last two decades, in particular in the context of elliptic partial differential equations, matrix functions and Sylvester equations. Our aim is to provide a framework for the analysis of the off-diagonal singular values, focusing on the structures that can ensure an exponential decay of them. We see how this structures appears in the computation of matrix functions and in the execution of the cyclic reduction paving the way for a theoretical understanding of the preservation of the quasiseparable rank. We provide family of bounds that highlight which parameters of the model can affect the rate of decay. Finally, we show how to practically exploit the low quasiseparable rank using hierarchical matrices. === Everyone is welcome! -- --federico poloni Dipartimento di Informatica, Università di Pisa http://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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Optimization & Numerical Analysis seminars: Sterle
by Federico Poloni 14 Apr '16

14 Apr '16

Speaker: Claudio Sterle Affiliation: University “Federico II” of Naples Time: Friday, 29 April 2016, h. 14:30 Place: Sala Seminari Ovest, Dipartimento di Informatica, Università di Pisa Title: Flow intercepting facility location routing problem: formulation and branch-and-cut solving approach Abstract: In the last ten years the research activity on location-routing problem (LRP) has significantly increased and many effective exact and approximated approaches have been presented for its solution. Following from this, great attention has been also devoted to several variants of the LRP, most of them coming from real applications. In particular, with reference to the city logistic (CL) context, several variants of the LRP have been proposed to design single-tier and two-tier freight distribution systems. In this case, LRP location decisions concern the number and position of one or more types of logistic facilities, whereas, routing decisions, concern the definition of dedicated or multi-stop routes of homogeneous or heterogeneous vehicle fleets. However most of the present literature deals with single-commodity LRP, whereas the multi-commodity case is still scarcely investigated. This issue can assume an important role in LRP real applications and in particular in the CL context. Indeed the freight to be distributed in an urban area are highly heterogeneous and consequently the problem is inherently multi-commodity. In order to contribute to fill this gap, an original formulation for the multi-commodity LRP is presented. The problem is referred to as the flow intercepting facility location-routing problem (FIFLOR), since its formulation is obtained merging the flow intercepting facility location and the vehicle routing models. A branch-and-cut algorithm for its solution is described and results obtained on test instances reproducing different urban network topologies are discussed. === Everyone is welcome! -- --federico poloni Dipartimento di Informatica, Università di Pisa http://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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Reminder: Optimization and numerical analysis seminars
by Federico Poloni 08 Apr '16

08 Apr '16

Speaker: Yaroslav D. Sergeyev Affiliation: Università della Calabria and N.I. Lobachevsky University of Nizhni Novgorod, Russia. Time: Monday, 11 April 2016, 15:00 Place: Sala Seminari Ovest, Dipartimento di Informatica, Università di Pisa Title: Lipschitz global optimization Abstract: http://pages.di.unipi.it/fpoloni/files/seminari/Sergeyev.pdf and Time: Tuesday, 12 April 2016, 12:00 Place: Sala Seminari Ovest, Dipartimento di Informatica, Università di Pisa Title: The Infinity Computer and numerical computations with infinities and in infinitesimals Abstract: http://pages.di.unipi.it/fpoloni/files/seminari/Sergeyev_Infinity.pdf === Everyone is welcome! -- --federico poloni Dipartimento di Informatica, Università di Pisa http://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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Cena di giovedì 7 Aprile
by massei＠student.dm.unipi.it 05 Apr '16

05 Apr '16

Cari tutti, in occasione della partenza di Raf Vandebril e come scusa per stare un po' insieme, si pensava di fare una cena giovedì sera alla trattoria di Montemagno [1]. Chi ha piacere di partecipare è ben accetto. Dovreste però comunicarmi chi viene e se ha un mezzo a disposizione, così prenoto e ci organizziamo per raggiungere il posto. A presto e buona giornata, Stefano [1] https://www.tripadvisor.it/Restaurant_Review-g580236-d1867657-Reviews-Tratt…

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Optimization & Numerical Analysis seminars: Sergeyev
by Federico Poloni 30 Mar '16

30 Mar '16

Speaker: Raf Vandebril Affiliation: KU Leuven Time: Thursday, April 7, h. 10:00 Place: Sala Seminari Ovest, Dipartimento di Informatica, Università di Pisa Title: A framework for structured linearizations of matrix polynomials in various bases Abstract: We present a framework for the construction of linearizations for scalar and matrix polynomials based on dual bases which, in the case of orthogonal polynomials, can be described by the associated recurrence relations. The framework provides an extension of the classical linearization theory for polynomials expressed in non-monomial bases and allows to represent polynomials expressed in product families, that is, as a linear combination of elements of the form $\phi_i(x) \psi_j(x)$, where $\{ \phi_i(x) \}$ and $\{ \psi_j(x) \}$ can either be polynomial bases or polynomial families which satisfy some mild assumptions. We show that this general construction can be used for many different purposes. Among them, we show how to linearize sums of polynomials and rational functions expressed in different bases. As an example, this allows to look for intersections of functions interpolated on different nodes without converting them to the same basis. === Everyone is welcome! -- --federico poloni Dipartimento di Informatica, Università di Pisa http://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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Optimization & Numerical Analysis seminars: Sergeyev (II)
by Federico Poloni 24 Mar '16

24 Mar '16

Speaker: Yaroslav D. Sergeyev Affiliation: Università della Calabria and N.I. Lobachevsky University of Nizhni Novgorod, Russia. Time: Tuesday, 12 April 2016, 12:00 Place: Sala Seminari Ovest, Dipartimento di Informatica, Università di Pisa Title: The Infinity Computer and numerical computations with infinities and in infinitesimals Abstract: The lecture presents a recent methodology allowing one to execute numerical computations with finite, infinite, and infinitesimal numbers on a new type of a computer – the Infinity Computer – patented in EU, USA, and Russia (see [23]). The new approach is based on the principle ‘The whole is greater than the part’ (Euclid’s Common Notion 5) that is applied to all numbers (finite, infinite, and infinitesimal) and to all sets and processes (finite and infinite). It is shown that it becomes possible to write down finite, infinite, and infinitesimal numbers by a finite number of symbols as particular cases of a unique framework different from that of the non-standard analysis [...] http://pages.di.unipi.it/fpoloni/files/seminari/Sergeyev_Infinity.pdf === Everyone is welcome! -- --federico poloni Dipartimento di Informatica, Università di Pisa http://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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Optimization & Numerical Analysis seminars: Sergeyev
by Federico Poloni 17 Mar '16

17 Mar '16

Speaker: Yaroslav D. Sergeyev Affiliation: Università della Calabria and N.I. Lobachevsky University of Nizhni Novgorod, Russia. Time: Monday, 11 April 2016, 15:00 Place: Sala Seminari Ovest, Dipartimento di Informatica, Università di Pisa Title: Lipschitz global optimization Abstract: Global optimization is a thriving branch of applied mathematics and an extensive literature is dedicated to it (see e.g., [1–24]). In this lecture, the global optimization problem of a multidimensional function satisfying the Lipschitz condition over a hyperinterval with an unknown Lipschitz constant is considered. It is supposed that the objective function can be “black box”, multiextremal, and non-differentiable. It is also assumed that evaluation of the objective function at a point is a time-consuming operation. Many algorithms for solving this problem have been discussed in literature. They can be distinguished, for example, by the way of obtaining information about the Lipschitz constant and by the strategy of exploration of the search domain. Different exploration techniques based on various adaptive partition strategies are analyzed. [...] http://pages.di.unipi.it/fpoloni/files/seminari/Sergeyev.pdf === Everyone is welcome! -- --federico poloni Dipartimento di Informatica, Università di Pisa http://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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Seminari su Mathematica
by Francesco Romani 02 Mar '16

02 Mar '16

Nell’ambito del corso di Esperienze di programmazione saranno tenuti 4 seminari introduttivi di circa 2 ore sul linguaggio Mathematica. Mercoledì 9/3 11-13 Aula C1 Introduzione a Mathematica Mercoledì 16/3 11-13 Aula C1 Grafica con Mathematica Mercoledì 23/3 11-13 Aula C1 Programmazione in Mathematica Mercoledì 27/4 11-13 Aula C1 Calcolo Numerico con Mathematica La partecipazione è aperta a tutti e vi prego di diffondere l’informazione ad eventuali interessati. Grazie, saluti, FR ____________________________ Prof. Francesco Romani Dipartimento di Informatica Via Buonarroti 2, 56127 PISA, ITALY Tel +39-050-2212734 FAX +39-050-2212726 http://www.di.unipi.it/~romani

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Mathematica
by Francesco Romani 29 Feb '16

29 Feb '16

Anche quest’anno, all’interno del corso di Esperienze di Programmazione, faccio 4-5 seminari su Mathematica. L’orario è mercoledi 11-13 / Venerdi 16-18 Avendo una certra libertà per collocarli volevo sapere se qualcuno ha intenzione di seguirli e ha preferenze sugli orari. Grazie saluti Francesco ____________________________ Prof. Francesco Romani Dipartimento di Informatica Via Buonarroti 2, 56127 PISA, ITALY Tel +39-050-2212734 FAX +39-050-2212726 http://www.di.unipi.it/~romani

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Optimization & Numerical Analysis seminars: Masciotta
by Federico Poloni 29 Feb '16

29 Feb '16

Speaker: Andrea Masciotta Affiliation: Dipartimento di Matematica, Università di Pisa Time: Monday, 7 March 2016, 14:30 Place: Sala Seminari Ovest, Dipartimento di Informatica, Università di Pisa Title: Minimization algorithms for compressive sensing Abstract: Compressive sensing is a new approach to digital signals acquisition and processing. Its main aim is the reconstruction of sparse signals or images (i.e. with few significant coefficients) from what was previously believed to be incomplete information. Compressive sensing has many potential applications, not only limited to the analysis of signals or images. In this talk we will first describe the main theoretical properties of compressive sensing, then three solution algorithms based on \ell_1 minimization will be presented, along with numerical experiments to highlight the main characteristics of these three methods in the framework of compressive sensing. === Everyone is welcome! -- --federico poloni Dipartimento di Informatica, Università di Pisa http://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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