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Numerical analysis seminar: L.Q. Qi
by Federico Poloni 11 May '17

11 May '17

Speaker: Liqun Qi, The Hong Kong Polytechnic University, Department of Applied Mathematics Title: Tensor Analysis: Spectral Theory and Special Tensors Room: Sala Riunioni, Dipartimento di Matematica Time: Monday, June 12, 11:00 Abstract: Eigenvalues for tensors were introduced in 2005. Since then, a rich theory on eigenvalues of tensors and special tensors has been developed. There are two main definitions of eigenvalues of tensors. One definition is based upon homogeneous polynomial systems. This definition extends the definition of eigenvalues of matrices. A complex number is an eigenvalue of a ``square'' tensor if and only if it is a root of the characteristic polynomial of that tensor. The sum of all the eigenvalues of that tensor is equal to the sum of the diagonal entries of that tensor, while the product of all the eigenvalues of that tensor is equal to the determinant of that tensor. An eigenvalue of a real tensor with a real eigenvector is called an H-eigenvalue. An even order real symmetric tensor is positive semi-definite if and only if all of its H-eigenvalues are nonnegative. Various tensor eigenvalue inclusion theorems have been developed. Another tensor eigenvalue definition has the merit that the eigenvalues under this definition are invariant under orthonormal transformations. This makes eigenvalues under this definition found their applications in engineering, physics and mechanics. Based upon the tensor eigenvalue theory, theories on special tensors have also been developed. In particular, the Perron-Frobenius theory for irreducible nonnegative tensors and weakly irreducible nonnegative tensors has been developed, and found applications in spectral hypergraph theory and higher order Markov chains. Other special tensors include positive semi-definite tensors, sum-of-squares tensors, completely positive tensors and copositive tensors, etc. Eigenvalues of tensors also found their applications in magnetic resonance imaging, elastic mechanics, liquid crystal study, quantum entanglement and classicality problems, etc. A book “Tensor Analysis: Spectral Theory and Special Tensors'' is published by SIAM in April this year. ==== 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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Numerical Analysis Seminar: R. Vandebril
by Federico Poloni 04 Apr '17

04 Apr '17

Giorno: Lunedi' 10 Aprile Ora: 11:00 Luogo: Aula Seminari, Dip.to di Matematica Speaker: Raf Vandebril, KU Leuven Titolo: Eigenvalues and eigenvectors of matrix polynomials === 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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Seminario Michele Benzi in SNS
by Federico Poloni 21 Mar '17

21 Mar '17

Carissimi, mi segnala Giancarlo Bigi che giovedì prossimo 23 marzo alle ore 14:30 ci sarà un seminario di Michele Benzi alla Scuola Normale: Fast iterative solution methods for the incompressible Navier-Stokes equations Giovedì, 23 Marzo 2017 Ore 14:30 Aula Maria Curie (SNS) Michele Benzi (Emory University) http://www.sns.it/seminari/fast-iterative-solution-methods-incompressible-n… (Abstract su http://www.sns.it/sites/default/files/allegati/15-03-2017/2017_03_23_benzi.…) Arrivederci, -- --federico poloni Dipartimento di Informatica, Università di Pisa http://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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workshop a Pisa, "matrix equations and tensor techniques"
by Federico Poloni 01 Feb '17

01 Feb '17

Ciao, il prossimo Febbraio al polo Fibonacci organizziamo uno workshop di due giorni, chiamato matrix equations and tensor techniques. All'edizione precedente a Bologna c'erano diversi partecipanti e speaker anche dall'estero (http://mett15.dm.unibo.it/schedule.html), e ci aspettiamo qualcosa di simile anche quest'anno. Se siete interessati a partecipare, o anche a sottomettere un talk, vi invitiamo a registrarvi (gratuitamente) su http://delone.dm.unipi.it/mett17. La scadenza per sottomettere talk è il 4 dicembre, quella per registrarsi è il 27 gennaio. Un saluto, -- --federico poloni Dipartimento di Informatica, Università di Pisa http://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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Call for Papers DAPS: Data Mining for Science of Success
by Luca Pappalardo 13 Jul '16

13 Jul '16

*Call for papers* *DAPS2016: The First International Workshop on Data mining for the Analysis of Performance and Success*, in conjunction with the IEEE International Conference on Data Mining (ICDM) Website: http://kdd.isti.cnr.it/daps2016/ Date: December 12, 2016, Barcelona, Spain The increasing availability of Big Data provides an unprecedented opportunity to explore the patterns underlying success. From the strategies followed by successful sportsmen to the emergence of runaway videos on YouTube, from popularity in social media to rising starts in the scientific enterprise, from widespread technologies to groundbreaking innovations, there is wealth of data that can be explored to answer common questions: How can we measure performance? What are the common patterns of success? How did successful individuals and products get to the top? What are the principles driving the dynamics of success? These are the challenging questions at the core of the emerging *Science of Success*, an interdisciplinary field that is attracting scientists from different scientific backgrounds. The purpose of this workshop is to bring together researchers from a variety of areas, all working on the problem of analyzing and understanding the patterns of success, though from different angles. The aim is to discuss: 1) the recently developed machine learning and data mining techniques that can be leveraged to address challenges in analyzing performance and success, and 2) starting from challenges in analyzing performance and success, the practical research directions in the machine learning and data mining community. The best papers of the workshop will be invited to contribute to a special issue on "Performance and Success" edited by the journal Complexity. For more information visit the workshop website: http://kdd.isti.cnr.it/daps2016, and the ICDM conference website: http://icdm2016.eurecat.org/. You can follow news about DAPS2016 on Twitter (@DAPSworkshop) and Facebook (https://www.facebook.com/DAPSworkshop/) *Important Dates:* - *Paper Submission: August 01, 2016, 23:59 PST* - Notification: September 13, 2016 - Camera ready: September 20, 2016 - Workshop: December 12, 2016 *Topics of interest:* We encourage submissions on all theoretical and practical aspects, as well as experimental studies of deployed systems. Topics of interest to the workshop include, but are not limited to, the following subject categories: - Science of Success - Big Data sources for performance and success - mathematical models of success, performance and their interplay - ranking algorithms for performance and success - patterns of success in the scientific enterprise - popularity dynamics of popularity ion social media (hashtags, viral videos, etc.) - definition and analysis of success in social networks - measures of performance and success in sports - data mining for sports analytics - anomaly, doping and fraud detection in sports performance - patterns of success in visual arts, music and writing - adoption, diffusion and success of innovations, products and technologies - novel approaches for detecting innovators and influencers - novel approaches for performance sensing and analysis - design of predictive models for performance and success - opinion mining and sentiment analysis to quantify success in social media - career success and longevity in different professions - analysis of collective success, and well-being, and development - mathematical models of success, performance and their interplay - role of networks in success *Contact information:* For problems or questions, please do not hesitate to contact the workshop organizers by email: - Luca Pappalardo: lpappalardo(a)di.unipi.it - Paolo Cintia: paolo.cintia(a)isti.cnr.it - Roberta Sinatra: sinatrar(a)ceu.edu

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Optimization & Numerical Analysis seminars: Flores-Bazan
by Federico Poloni 23 Jun '16

23 Jun '16

Speaker: Fabián Flores Bazán Affiliation: Departamento de Ingeniería Matemática, Universidad de Concepción, Chile Time and date: Monday, 4th July 2016, 15:00 Place: Sala Seminari Est, Dipartimento di Informatica, Università di Pisa Title: A semi-infinite programming approach for the circular conic StQOP: strong duality, optimality and hidden convexity Abstract: Many formulations of quadratic allocation problems, portfolio optimization problems, the maximum weight clique problem, among others, take the form as the well-known standard quadratic optimization problem, which consist in minimizing a homogeneous quadratic function on the usual simplex in the non negative orthant. We propose to analyze the same problem when the simplex is substituted by a convex and compact base of any pointed, closed, convex (possibly circular) cone. It is associated three main duals (for which a semi-infinite formulation of the primal problem is required) and establish some characterizations of strong duality with respect to each of the three duals in terms of copositivity of the Hessian of the quadratic objective function on suitable cones. Such a problem reveals a hidden convexity. Part of the results were obtained jointly with G. Cárcamo and S. Caro. This research is supported in part by CONICYT-Chile through FONDECYT 115-0973 and BASAL projects, CMM, Universidad de Chile. === 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: Romani
by Federico Poloni 20 Jun '16

20 Jun '16

Speaker: Francesco Romani Affiliation: Scuola Normale Superiore, Pisa Time: Monday, 20 June 2016, h. 10:00 Place: Sala Seminari Ovest, Dipartimento di Informatica, Università di Pisa Title: Algoritmi adattivi per il Clustering convesso e non convesso basato sulla NMF simmetrica Abstract: Vengono presentati algoritmi adattivi basati sulla fattorizzazione simmetrica non negativa di matrici sia per il caso di cluster con inviluppo convesso che di cluster qualsiasi. A parte il calcolo delle distanze tra i punti, gli algoritmi non fanno uso di nozioni geometriche. Lavoro congiunto con Paola Favati (CNR), Grazia Lotti (Università di Parma), Ornella Menchi http://pages.di.unipi.it/fpoloni/files/seminari/romani.doc === 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: Seminario Clustering
by Francesco Romani 20 Jun '16

20 Jun '16

Speaker: Francesco Romani Time: Monday, 20 June 2016, h. 10:00 Place: Sala Seminari Ovest, Dipartimento di Informatica, Università di Pisa Title: Algoritmi adattivi per il Clustering convesso e non convesso basati sulla NMF simmetrica Lavoro congiunto con Paola Favati (CNR), Grazia Lotti (Università di Parma), Ornella Menchi ____________________________ 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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Fwd: Reminder: Seminario Clustering
by Francesco Romani 20 Jun '16

20 Jun '16

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Reminder: Optimization & Numerical Analysis seminars: Brugiapaglia
by Federico Poloni 20 Jun '16

20 Jun '16

Speaker: Simone Brugiapaglia Affiliation: Politecnico di Milano --- Laboratory for Modeling and Scientific Computing MOX Time: Tuesday, December 15, 11 am Place: Sala Seminari Est, Dipartimento di Informatica, Università di Pisa Title: CORSING: Sparse approximation of PDEs based on Compressed Sensing Abstract: We present a novel method for the numerical approximation of PDEs, motivated by recent developments in sparse representation, and particularly by compressed sensing. We named this approach CORSING (COmpRessed SolvING). Establishing an analogy between the sampling of a signal and the Petrov-Galerkin discretization of a PDE, the CORSING method can recover the best s-term approximation to the solution with respect to N suitable trial functions, with s<<N, by evaluating the bilinear form associated with the PDE against a randomized choice of m<<N test functions. This yields an underdetermined m x N linear system, that is solved by means of sparse optimization techniques. A theoretical analysis of the CORSING procedure is presented, based on the concepts of local a-coherence and restricted inf-sup property, along with numerical experiments that confirm the robustness and reliability of the proposed strategy. === Everyone is welcome! -- --federico poloni

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