- NumPI - Mailing list — Dipartimento di Matematica, UniPI

seminario Beneventano domani
by Beatrice Meini 12 Jan '26

12 Jan '26

Buonasera, scusate lo scarso preavviso. Domani alle 14, in Saletta Riunioni al Dip Matematica, Pierfrancesco Beneventano, un nostro ex studente e ora post-doc a MIT, terra' il seminario: Edge of Stochastic Stability: SGD does not train neural networks as you expect it https://www.dm.unipi.it/en/seminar/?id=694aba9c2ac7f6b23978e5a0 Saluti, Beatrice

1 0

Fw: Talk by Davide Palitta - January 19th
by Fabio Durastante 05 Jan '26

05 Jan '26

Dear all, I am forwarding the announcement below from the FLorence OPtimization talkS (FLOPS) mailing list, as the topic may be of interest to many of you. Please find the details of the seminar hereunder. Best, Fabio ________________________________ Da: FLOPtalks <floptalks-group(a)unifi.it> Inviato: lunedì, gennaio 5, 2026 4:02:44 PM A: FLOPtalks <floptalks-group(a)unifi.it> Cc: davide.palitta(a)unibo.it <davide.palitta(a)unibo.it> Oggetto: Talk by Davide Palitta - January 19th Dear colleagues and friends, we are pleased to announce the next seminar of the FLorence OPtimization talkS (FLOPS) series. Davide Palitta<https://www.unibo.it/sitoweb/davide.palitta>, RTDb at Università di Bologna, will give a talk entitled "The S^T-S-SVD and Applications". The talk will be on January 19th at 11:00 a.m. in Room 119 Centro didattico Morgagni<https://g.co/kgs/uuxpeDA>. The abstract of the talk is available at the following link<https://sites.google.com/unifi.it/floptalks/home?authuser=3> (as well as in the attached poster). Best regards, Margherita & Marianna -- You received this message because you are subscribed to the Google Groups "FLOPtalks" group. To unsubscribe from this group and stop receiving emails from it, send an email to floptalks-group+unsubscribe(a)unifi.it<mailto:floptalks-group+unsubscribe@unifi.it>. To view this discussion, visit https://groups.google.com/a/unifi.it/d/msgid/floptalks-group/9e7571c1-e9ab-…<https://groups.google.com/a/unifi.it/d/msgid/floptalks-group/9e7571c1-e9ab-…>.

1 0

Fwd: Talk by Simone Rebegoldi - December 11th (FLOPS)
by Fabio Durastante 04 Dec '25

04 Dec '25

Dear all, I am forwarding the announcement below from the FLorence OPtimization talkS (FLOPS) mailing list, as the topic may be of interest to many of you. Please find the details of the seminar hereunder. Best, Fabio -------- Messaggio Inoltrato -------- Oggetto: Talk by Simone Rebegoldi - December 11th Data: Thu, 4 Dec 2025 07:33:55 -0800 (PST) Mittente: FLOPtalks <floptalks-group(a)unifi.it> A: FLOPtalks <floptalks-group(a)unifi.it> CC: srebegoldi(a)unimore.it Dear colleagues and friends, we are pleased to announce the next seminar of the FLorence OPtimization talkS (FLOPS) series. Simone Rebegoldi <https://unimore.unifind.cineca.it/resource/person/113208>, RTDb at Università degli studi di Modena e Reggio Emilia,will give a talk entitled "On the convergence and stability of multiscale decompositions for imaging inverse problems". The talk will be on *December** 11th at 11:15 a.m. *in**Room 007 Centro didattico Morgagni <https://g.co/kgs/uuxpeDA>. The abstract of the talk is available at the following link <https://sites.google.com/unifi.it/floptalks/home?authuser=3> (as well as in the attached poster). Best regards, Margherita & Marianna -- You received this message because you are subscribed to the Google Groups "FLOPtalks" group. To unsubscribe from this group and stop receiving emails from it, send an email to floptalks-group+unsubscribe(a)unifi.it. To view this discussion, visit https://groups.google.com/a/unifi.it/d/msgid/floptalks-group/d52c826d-332d-… <https://groups.google.com/a/unifi.it/d/msgid/floptalks-group/d52c826d-332d-…>.

1 0

HPSC Colloquia - Darya Majidi - L’Intelligenza Artificiale per costruire un futuro digitale, etico, ed inclusivo
by Fabio Durastante 13 Nov '25

13 Nov '25

Inizia il ciclo di incontri “HPSC Colloquia”, organizzato dal dottorato in "High Performance Scientific Computing”, in collaborazione con il ciclo di incontri "Matematici al Lavoro", in cui I nostri studenti hanno l'opportunità di confrontarsi con professionisti e scoprire le diverse carriere verso cui i percorsi formativi del nostro ateneo possono portare. Scrivo per ricordarvi del prossimo appuntamento, che sarà Mercoledì 19 Novembre alle ore 11:00 nell'Aula Magna del Dipartimento di Matematica, e online al link: https://meetings.dm.unipi.it/b/luc-bw9-xim-ayo Ospite dell'incontro sarà Darya Majidi, President UN Women Italy - Fortune Italia Most Powerful Women 2023 - CEO Daxo Group - Founder Donne 4.0 - Italian/Iranian Entrepreneur with 30 years in digital transformation & AI - Board Member - Speaker - Author. Darya terrà una conferenza dal titolo: "L’Intelligenza Artificiale per costruire un futuro digitale, etico, ed inclusivo" (di cui l'abstract è riportato sotto) L'incontro si concluderà con un dibattito e una sessione di domande e risposte, un momento prezioso per interagire direttamente con l'ospite. Tutti gli interessati sono caldamente invitati a partecipare. Non esitate a rispondere a questa email per ulteriori informazioni. Cordiali Saluti per HPSC: Luca Heltai, Giuseppe Felici per Matematici al lavoro: Stefano Galatolo, Silvia Gazzola, Marco Romito Titolo: "L’Intelligenza Artificiale per costruire un futuro digitale, etico, ed inclusivo” ABSTRACT L’intelligenza artificiale rappresenta una delle più potenti trasformazioni della nostra epoca, capace di ridefinire non solo i modelli economici e scientifici, ma anche i valori fondamentali che orientano le società umane. L’intervento propone una riflessione sulla costruzione di un’intelligenza artificiale al servizio dell’uomo, etica, trasparente e inclusiva. Verranno affrontati i temi di machine learning, reti neurali, etica, bias nei dati e e dell’importanza di un approccio multidisciplinare che integri competenze tecniche, etiche e sociali. L’obiettivo è stimolare nei ricercatori una consapevolezza critica e un impegno attivo nella progettazione di tecnologie che promuovano equità, sostenibilità e rispetto dei diritti umani.

1 0

[Indico] Kai Bergermann, Numerical linear algebra meets multiplex networks, 13/11/2025, 11:00 Europe/Rome
by fabio.durastante＠unipi.it 12 Nov '25

12 Nov '25

Title: Numerical linear algebra meets multiplex networks, Speaker(s): Kai Bergermann, Scuola Normale Superiore, Date and time: 13 Nov 2025, 11:00 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Department of Mathematics (Sala Riunioni). You can access the full event here: https://events.dm.unipi.it/e/329 Abstract -------- Multiplex networks are used to model complex systems from myriad applications. They generalize classical complex networks by recording different types of relationships, different interactions, or changing interactions over time between the same entities in different layers. They possess natural linear algebraic representations in terms of structured matrices, which makes efficient numerical linear algebra techniques a valuable tool for their analysis. In this talk, I will present contributions to multiplex network analysis relying on matrix function approximation and nonlinear spectral methods. I will discuss centrality measures, the solution of stiff systems of non-linear differential equations with exponential Runge--Kutta integrators, un- and semi-supervised community detection, and core-periphery detection. All presented methods have a linear runtime scaling, which allows the treatment of large-scale multiplex networks and numerical experiments for all considered problems will be presented. -- Indico :: Email Notifier https://events.dm.unipi.it/e/329

1 0

[Indico] Prof. Luca Heltai, An overview of non-matching coupling algorithm for High Performance Finite Element Applications, 11/11/2025, 14:00 Europe/Rome
by fabio.durastante＠unipi.it 10 Nov '25

10 Nov '25

Title: An overview of non-matching coupling algorithm for High Performance Finite Element Applications, Speaker(s): Prof. Luca Heltai, Università di Pisa, Date and time: 11 Nov 2025, 14:00 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Aula Seminari). Address: Largo Bruno Pontecorvo, 5, 56127 Pisa PI You can access the full event here: https://events.dm.unipi.it/e/333 Abstract -------- This seminar presents an overview of non-matching coupling algorithms for high-performance finite element applications, with emphasis on implementation and preconditioning aspects. We address ficitious domain, immersed boundary, and mixed-dimensional problems on non-matching grids, as arise in coupled PDE systems defined on heterogeneous domains. We derive different formulations and show how most of them can be traced back to variations or stabilizations of the Lagrange multiplier and distributed Lagrange multiplier frameworks. We discuss various implementation aspects of the problem, including exact and inexact integration across non-matching grids, matrix based and matrix-free transfer operators, particle-based transfer operators, and discuss briefly some augmented Lagrangian-based preconditioners, designed to yield optimal and scalable convergence properties when used in conjunction with iterative Krylov solvers. Finally, we discuss what is the current status of the implementation for these solvers within the deal.II finite element library. StreamingThe seminar will also be broadcast online at the link: https://meetings.dm.unipi.it/b/luc-kwc-keb-p9k Note ---- Reminder -- Indico :: Email Notifier https://events.dm.unipi.it/e/333

1 0

[Indico] Prof. Luca Heltai, An overview of non-matching coupling algorithm for High Performance Finite Element Applications, 11/11/25, 2:00 PM Europe/Rome
by fabio.durastante＠unipi.it 06 Nov '25

06 Nov '25

Title: An overview of non-matching coupling algorithm for High Performance Finite Element Applications, Speaker(s): Prof. Luca Heltai, Università di Pisa, Date and time: Nov 11, 2025, 2:00 PM (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Aula Seminari). Address: Largo Bruno Pontecorvo, 5, 56127 Pisa PI You can access the full event here: https://events.dm.unipi.it/e/333 Abstract -------- This seminar presents an overview of non-matching coupling algorithms for high-performance finite element applications, with emphasis on implementation and preconditioning aspects. We address ficitious domain, immersed boundary, and mixed-dimensional problems on non-matching grids, as arise in coupled PDE systems defined on heterogeneous domains. We derive different formulations and show how most of them can be traced back to variations or stabilizations of the Lagrange multiplier and distributed Lagrange multiplier frameworks. We discuss various implementation aspects of the problem, including exact and inexact integration across non-matching grids, matrix based and matrix-free transfer operators, particle-based transfer operators, and discuss briefly some augmented Lagrangian-based preconditioners, designed to yield optimal and scalable convergence properties when used in conjunction with iterative Krylov solvers. Finally, we discuss what is the current status of the implementation for these solvers within the deal.II finite element library. StreamingThe seminar will also be broadcast online at the link: https://meetings.dm.unipi.it/b/luc-kwc-keb-p9k -- Indico :: Email Notifier https://events.dm.unipi.it/e/333

1 0

[Indico] Kai Bergermann, Numerical linear algebra meets multiplex networks, 13/11/2025, 11:00 Europe/Rome
by fabio.durastante＠unipi.it 03 Nov '25

03 Nov '25

Title: Numerical linear algebra meets multiplex networks, Speaker(s): Kai Bergermann, Scuola Normale Superiore, Date and time: 13 Nov 2025, 11:00 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Department of Mathematics (Sala Riunioni). You can access the full event here: https://events.dm.unipi.it/e/329 Abstract -------- Multiplex networks are used to model complex systems from myriad applications. They generalize classical complex networks by recording different types of relationships, different interactions, or changing interactions over time between the same entities in different layers. They possess natural linear algebraic representations in terms of structured matrices, which makes efficient numerical linear algebra techniques a valuable tool for their analysis. In this talk, I will present contributions to multiplex network analysis relying on matrix function approximation and nonlinear spectral methods. I will discuss centrality measures, the solution of stiff systems of non-linear differential equations with exponential Runge--Kutta integrators, un- and semi-supervised community detection, and core-periphery detection. All presented methods have a linear runtime scaling, which allows the treatment of large-scale multiplex networks and numerical experiments for all considered problems will be presented. -- Indico :: Email Notifier https://events.dm.unipi.it/e/329

1 0

Colloquium Daniela Calvetti
by Silvia Gazzola 20 Oct '25

20 Oct '25

Cari tutte e tutti, Vi scrivo per segnalarvi che, la prossima settimana, Daniela Calvetti<https://mathstats.case.edu/faculty/daniela-calvetti/> sarà in visita presso il nostro dipartimento. In particolare, lunedì 27 ottobre, alle ore 16, presso l'Aula Magna del Dipartimento di Matematica, terrà un colloquium dal titolo: `Linear algebra joins probability in the search for sparse and group sparse solutions with few data’. Trovate ulteriori dettagli al link: https://www.dm.unipi.it/en/seminar/?id=68f20c6cdefecee83efcca3e Fatemi pur anche sapere se desiderate interagire con Daniela Calvetti intanto che si trova a Pisa. Cordiali saluti, Silvia ============= Dr Silvia Gazzola Dipartimento di Matematica Università di Pisa https://sites.google.com/view/silviaspersonalwebpage/silvias-homepage ---------------------------------------------------------------------------------------------------------------------------------------------------------- You may receive this email outside my normal working hours — no response is expected outside your working hours ----------------------------------------------------------------------------------------------------------------------------------------------------------

1 0

Seminario Fabio Credali - 25 Settembre 2025 - ore 12.00
by Luca Heltai 17 Sep '25

17 Sep '25

Car* tutt*, vi scrivo per segnalare un seminario che si terrà il 25 Settembre alle ore 12.00 in Sala riunioni presso il dipartimento di Matematica: Speaker: Dr. Fabio Credali, King Abdullah University of Science and Technology - KAUST Title: Advances on the finite element discretization of fluid-structure interaction problems Abstract: We review the main features of an unfitted finite element method for fluid-structure interaction problems based on a distributed Lagrange multiplier in the spirit of the fictitious domain approach. A coupling term describes the interaction between fluid and solid and it involves functions defined over two distinct non-matching grids, thus its evaluation is not trivial. We study the effect of exact and inexact integration by presenting quadrature estimates supported by numerical results. Moreover, we show that our method is stable even in presence of small cut cells and we provide an upper bound for the condition number. Finally, we outline the mass conservation properties of the proposed approach in the case of popular conforming finite element spaces. This work is a collaborative effort with Daniele Boffi, Lucia Gastaldi and Najwa Alshehri.

1 0

Convegno al Centro De Giorgi: Morphogenesis and morphing, 200 years after Gauss
by Luca Heltai 15 Sep '25

15 Sep '25

Cari tutti, vi giro le informazioni su un convegno molto interessante giratemi da Antonio De Simone. La deadline per la registrazione è oggi... Cordialmente, Luca. > Begin forwarded message: > > From: Antonio De Simone <antonio.desimone(a)santannapisa.it> > Subject: [Junk released by User action] Convegno al Centro De Giorgi: Morphogenesis and morphing, 200 years after Gauss > Date: 10 September 2025 at 12:53:19 CEST > To: Alessandro Tognetti <alessandro.tognetti(a)unipi.it>, Roberto Paroni <rob.paroni(a)gmail.com>, Simone Camarri <simone.camarri(a)unipi.it>, "luca.heltai(a)unipi.it" <luca.heltai(a)unipi.it> > > Cari Roberto, Alessandro, Simone, Luca, > > il 20-24 ottobre prossimi organizzo un convegno internazionale al Centro De Giorgi della Scuola Normale Superiore, insieme ai matematici: > > https://indico.sns.it/event/122/ > https://indico.sns.it/event/122/ > > Sarà un convegno di alto livello, molto interdisciplinare e penso che potrebbe essere interessante per molti ricercatori e studenti a UniPI. > Posso chiedervi la cortesia di diffondere questa informazione attraverso i canali della vostra università e dei vostri dipartimenti? > Occorre registrarsi alla pagina web qui sotto: > > https://indico.sns.it/event/122/registrations/69/ > > Ovviamente siete invitantissimi a partecipare. > Grazie mille e cari saluti, > Antonio > > *** English Version*** > International worship at Centro De Giorgi, Pisa > 20-24 October 2025 > Morphogenesis and morphing, 200 years after Gauss: > > On October 20-24 there will be an interesting and high level international workshop at Centro De Giorgi (Scuola Normale Superiore, Pisa) entitled: > Morphogenesis and morphing, 200 years after Gauss: > > https://indico.sns.it/event/122/ > > Registration is required, via the following webpage: > > https://indico.sns.it/event/122/registrations/69/ > > Thank you and best wishes, > Antonio DeSimone > ****

1 0

posizione dottorato Aalto university
by Federico Poloni 01 Jul '25

01 Jul '25

Cari tutti, Vanni Noferini mi segnala questa posizione di dottorato su “Matrix nearness problems via Riemannian optimisation’’: https://www.aalto.fi/en/open-positions/doctoral-candidate-in-applied-mathem… Inoltro qui, anche se è in concorrenza con le nostre a Pisa in Matematica e HPSC ( https://www.dm.unipi.it/bandi-di-concorso-per-lammissione-ai-dottorati-di-r… ). Un caro saluto, Federico -- --Federico Poloni Dipartimento di Informatica, Università di Pisa https://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

1 0

Nello Cristianini a Pisa
by Gianna M. Del Corso 20 May '25

20 May '25

Cari colleghi, Giovedì 22/5 alle 11:00 nell’aula magna dell’ex facoltà di Scienze, Nello Cristianini, professore di intelligenza artificiale all’ Università di Bath terrà una presentazione del suo libro "Machina Sapiens <https://www.mulino.it/isbn/9788815384461>” discutendo dei rischi e delle implicazioni dell'AI generativa. Sarà un'ottima occasione per approfondire temi di grande attualità nel nostro campo con uno dei principali esperti dell'argomento, che li presenterà in modo accessibile. Vi incoraggio a partecipare e a contribuire alla discussione, invitando anche gli studenti del nostro corso di laurea. Cordiali saluti, Gianna @@@@@@@@@@@@@@@@@ Gianna M. Del Corso, PhD Dipartimento di Informatica, Università di Pisa Largo Pontecorvo, 3 56127 Pisa, Italy ph. +39-050-2213118 @@@@@@@@@@@@@@@@@

1 0

[Indico] Federica Mugnaioni, Optimal and Scalable Augmented Lagrangian preconditioners for Fictitious Domain problems, 13/05/2025, 11:00 Europe/Rome
by fabio.durastante＠unipi.it 12 May '25

12 May '25

Title: Optimal and Scalable Augmented Lagrangian preconditioners for Fictitious Domain problems, Speaker(s): Federica Mugnaioni, Scuola Normale Superiore, Date and time: 13 May 2025, 11:00 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Saletta Riunioni). You can access the full event here: https://events.dm.unipi.it/e/321 Abstract -------- One of the major drawbacks of using Fictitious Domain methods is the computational demands of solving the associated large-scale linear systems, both in terms of time and memory. To address this issue, we propose two augmented Lagrangian-based preconditioners for efficiently solving linear systems of equations with a block two-by-two and three-by-three structure arising from fictitious domain problems and from finite element discretizations of immersed boundary methods. We consider two relevant examples to illustrate the performance of these preconditioners when used in conjunction with flexible GMRES: the Poisson and the Stokes fictitious domain problems. We provide a detailed spectral analysis, deriving lower and upper bounds for the eigenvalues of the preconditioned matrix and showing their independence with respect to discretization parameters. Furthermore, we discuss the eigenvalue distribution when inexact versions of the preconditioners are employed. We show the effectiveness of the proposed approach and the robustness of our preconditioning strategies through extensive numerical tests in both two and three dimensions, using different immersed geometries.M. Benzi, M. Feder, L. Heltai and F. Mugnaioni. Optimal and Scalable Augmented Lagrangian preconditioners for Fictitious Domain problems. arXiv:2504.11339, 2025 Note ---- A reminder of tomorrow's seminar. -- Indico :: Email Notifier https://events.dm.unipi.it/e/321

1 0

[Indico] Federica Mugnaioni, Optimal and Scalable Augmented Lagrangian preconditioners for Fictitious Domain problems, 13/05/2025, 11:00 Europe/Rome
by fabio.durastante＠unipi.it 28 Apr '25

28 Apr '25

Title: Optimal and Scalable Augmented Lagrangian preconditioners for Fictitious Domain problems, Speaker(s): Federica Mugnaioni, Scuola Normale Superiore, Date and time: 13 May 2025, 11:00 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Saletta Riunioni). You can access the full event here: https://events.dm.unipi.it/e/321 Abstract -------- One of the major drawbacks of using Fictitious Domain methods is the computational demands of solving the associated large-scale linear systems, both in terms of time and memory. To address this issue, we propose two augmented Lagrangian-based preconditioners for efficiently solving linear systems of equations with a block two-by-two and three-by-three structure arising from fictitious domain problems and from finite element discretizations of immersed boundary methods. We consider two relevant examples to illustrate the performance of these preconditioners when used in conjunction with flexible GMRES: the Poisson and the Stokes fictitious domain problems. We provide a detailed spectral analysis, deriving lower and upper bounds for the eigenvalues of the preconditioned matrix and showing their independence with respect to discretization parameters. Furthermore, we discuss the eigenvalue distribution when inexact versions of the preconditioners are employed. We show the effectiveness of the proposed approach and the robustness of our preconditioning strategies through extensive numerical tests in both two and three dimensions, using different immersed geometries.M. Benzi, M. Feder, L. Heltai and F. Mugnaioni. Optimal and Scalable Augmented Lagrangian preconditioners for Fictitious Domain problems. arXiv:2504.11339, 2025 -- Indico :: Email Notifier https://events.dm.unipi.it/e/321

1 0

Colloquium 17 aprile ore 16.00
by Stefano Massei 15 Apr '25

15 Apr '25

Cari tutti, a nome della Commissione Colloquia di Dipartimento, vi ricordo che giovedì 17 aprile alle 16.00 in AULA MAGNA Virginie Ehrlacher<https://team.inria.fr/matherials/team-members/virginie-ehrlacher-galland/> (Ecole des Ponts ParisTech) terrà un <https://www.dm.unipi.it/en/seminar/?id=67a64aff762f5b32f7b4dfd3> colloquium<https://www.dm.unipi.it/en/seminar/?id=67a64aff762f5b32f7b4dfd3> sul tema: “A sparse approximation of the Lieb functional with moment constraints”. Cordiali saluti, Stefano Massei

1 0

Next NUMPI seminar: set the date
by Fabio Durastante 15 Apr '25

15 Apr '25

Good morning, We would like to fix the date for the next NUMPI seminar in May. It will be a seminar held by Federica Mugnaioni (Ph.D. Scuola Normale Superiore) on the topic of preconditioners for discretization of fictitious domain problems. Please reply with your availability for the days of May 12/13 and we will try to organize it at a time convenient for most of us: https://date.dm.unipi.it/Vh6AwjL3MKGWBESp Best, Fabio

1 0

[Indico] Raf Vandebril, On inverse eigenvalue problems for multiple orthogonal polynomials, 14/04/2025, 11:30 Europe/Rome
by leonardo.robol＠unipi.it 14 Apr '25

14 Apr '25

Title: On inverse eigenvalue problems for multiple orthogonal polynomials, Speaker(s): Raf Vandebril, KU Leuven, Date and time: 14 Apr 2025, 11:30 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Saletta Riunioni). You can access the full event here: https://events.dm.unipi.it/e/318 Abstract -------- Multiple orthogonal polynomials (MOP's) arise in various applications, including approximation theory, random matrix theory, and numerical integration. To define MOP's, one needs multiple inner products, leading to two types of MOP’s, which are mutually biorthogonal. These MOP's satisfy recurrence relations, which can be linked to linear algebra, via discretization. As a result we get an inverse eigenvalue problem to retrieve the matrix of recurrences directly. We provide two algorithms for solving the inverse eigenvalue problem, one based on classical equivalence transformations and one linked to (block) Krylov methods. Numerical illustrations are provided to demonstrate correctness of the approach and also reveal the strong sensitivity of the problem. -- Indico :: Email Notifier https://events.dm.unipi.it/e/318

1 0

[Indico] Raf Vandebril, On inverse eigenvalue problems for multiple orthogonal polynomials, 14/04/2025, 11:30 Europe/Rome
by leonardo.robol＠unipi.it 08 Apr '25

08 Apr '25

Title: On inverse eigenvalue problems for multiple orthogonal polynomials, Speaker(s): Raf Vandebril, KU Leuven, Date and time: 14 Apr 2025, 11:30 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Saletta Riunioni). You can access the full event here: https://events.dm.unipi.it/e/318 Abstract -------- Multiple orthogonal polynomials (MOP's) arise in various applications, including approximation theory, random matrix theory, and numerical integration. To define MOP's, one needs multiple inner products, leading to two types of MOP’s, which are mutually biorthogonal. These MOP's satisfy recurrence relations, which can be linked to linear algebra, via discretization. As a result we get an inverse eigenvalue problem to retrieve the matrix of recurrences directly. We provide two algorithms for solving the inverse eigenvalue problem, one based on classical equivalence transformations and one linked to (block) Krylov methods. Numerical illustrations are provided to demonstrate correctness of the approach and also reveal the strong sensitivity of the problem. -- Indico :: Email Notifier https://events.dm.unipi.it/e/318

1 0

[Indico] Prof. Michiel Hochstenbach, Recent Progress in Steplengths in Gradient Methods for Unconstrained Optimization, 3/27/25, 2:00 PM Europe/Rome
by stefano.massei＠unipi.it 26 Mar '25

26 Mar '25

Title: Recent Progress in Steplengths in Gradient Methods for Unconstrained Optimization, Speaker(s): Prof. Michiel Hochstenbach, Eindhoven University of Technology, Date and time: Mar 27, 2025, 2:00 PM (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di matematica (Aula riunioni). You can access the full event here: https://events.dm.unipi.it/e/314 Abstract -------- We review recent progress in stepsizes in gradient methods for unconstrained numerical optimization, for both quadratic and general nonlinear problems, including several very valuable contributions from Italian experts such as Prof. Zanni and colleagues. We will review Barzilai-Borwein steps and secant equations, and show developments in harmonic stepsizes and homogeneous secant equations. The key idea is that the steplength is selected as the inverse Ritz value of an average Hessian. For limited memory methods, we will address several challenges, including how to avoid negative or non-real stepsize candidates. We will also present some open problems. This talk reflects joint work with Giulia Ferrandi. -- Indico :: Email Notifier https://events.dm.unipi.it/e/314

1 0

Discussione tesi di dottorato di Alberto Bucci
by Leonardo Robol 21 Feb '25

21 Feb '25

Cari tutti e tutte, lunedì 24/02, alle 10.00, Alberto Bucci discuterà la sua tesi di dottorato in Aula Magna del Dipartimento di Matematica. Il titolo della tesi è "Randomized techniques for low-rank approximation of matrices and tensors with applications". Chiunque volesse partecipare è benvenuto/a! A presto, -- Leonardo.

1 0

Online seminar at University of Rome "Tor Vergata": Stefano Pozza: 6 febbraio alle 12:30
by Fabio Durastante 29 Jan '25

29 Jan '25

Dear everybody, Forwarding of a NA seminar announcement that can also be followed online at the University of Rome "Tor Vergata". Best, Fabio ________________________________ Da: Mariarosa Mazza <mariarosa.mazza(a)uniroma2.it> Inviato: mercoledì 29 gennaio 2025 18:49 A: mariarosa.mazza(a)uniroma2.it Oggetto: seminario Pozza: 6 febbraio alle 12:30 Car* tutt*, giovedi 6 febbraio alle 12.30 in aula Dal Passo, Dipartimento di Matematica, Roma Tor Vergata, il Dott. Stefano Pozza (Charles University) terrà un seminario dal titolo (abstract in calce): "How to express the solution of an ODE as a linear system (in a suitable algebra) and exploit it for fast computation and network analysis". Il seminario può essere seguito online usando il link: https://teams.microsoft.com/l/meetup-join/19%3ad48916dee7364e0bbb08216ea621… Vi prego di diffondere l'annuncio fra i possibili interessati. Un caro saluto e grazie, Mariarosa --------------------------------------- Abstract: The solution of systems of non-autonomous linear ordinary differential equations is crucial in various applications, such as nuclear magnetic resonance spectroscopy. We introduced a new solution expression in terms of a generalization of the Volterra composition. Such an expression is linear in a particular algebraic structure of distributions, which can be mapped onto a subalgebra of infinite matrices. It is possible to exploit the new expression to devise fast numerical methods for linear non-autonomous ODEs. As a first example, we present a new method for the operator solution of the generalized Rosen-Zener model, a system of linear non-autonomous ODEs from quantum mechanics. The new method’s computing time scales linearly with the model’s size in the numerical experiments. A second example is the analysis of temporal network, where the new expression might lead to novel extension of subgraph centrality indexes. -- ------------------------------------- Dr. Mariarosa Mazza University of Rome Tor Vergata Via della Ricerca Scientifica, 1 00133, Rome, Italy Email: mariarosa.mazza(a)uniroma2.it<mailto:mariarosa.mazza@uniroma2.it> Tel: 0039 06-7259-4636 Url: https://sites.google.com/site/mariarosamazza1/ ---------------------------------

1 0

Online Seminar: Peter Taylor, "The Role of Physical Understanding in Matrix-Analytic Methods"
by Federico Poloni 14 Jan '25

14 Jan '25

In case someone is interested, let me share this online event. A flyer is attached. Speaker: Professor Peter Taylor, The University of Melbourne Date: Thursday, February 6 2025 Time: 22:00 Italian time (!!) Title: The Role of Physical Understanding in Matrix-Analytic Methods Abstract: Since Marcel Neuts first showed that Markov chains of GI/M/1 type have a matrix-geometric stationary distribution in the 1970s and 1980s, the interplay between analytic properties and physical interpretation has played a major part in the development of matrix-analytic methods for stochastic models. Most performance measures of interest in such models can be expressed in terms of the solutions of equations involving matrix power series, which have to be solved numerically. Over the years, various iterative algorithms have been proposed for doing this. In order to establish convergence, and gain information about the speed of convergence, it is often helpful to think about the physical interpretation of the iterates. I shall discuss the physical interpretation of matrix-analytic algorithms that have been proposed for analysing block-structured Markov additive models. -- --Federico Poloni Dipartimento di Informatica, Università di Pisa https://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

1 0

Lauri Nyman, "Riemann-Oracle: A framework for matrix nearness problems" 10/12/2024, 16:00
by Federico Poloni 10 Dec '24

10 Dec '24

The following seminar will take place next week; Lauri Nyman and Vanni Noferini from Aalto University are visiting the department of computer science in that week. Title: Riemann-Oracle: A framework for matrix nearness problems Speaker: Lauri Nyman, Aalto University, Espoo, Finland Where: Sala Seminari Est, Dipartimento di Informatica When: Tuesday December 10, 2024; 16:00 Abstract: In this talk, we propose a versatile approach for addressing a large family of matrix nearness problems. In these problems, the task is to find a matrix nearest to a given one that satisfies a desired constraint. The method is based on splitting a matrix nearness problem into two nested optimization problems, of which the inner one can be solved cheaply and exactly, while the outer one can be recast as an unconstrained optimization task over a smooth real Riemannian manifold. We also show that the objective function to be minimized on the Riemannian manifold can be discontinuous, thus requiring regularization techniques, and we give conditions for this to happen. Finally, we demonstrate the practical applicability of our method by implementing it for a number of matrix nearness problems that are relevant for applications, including nearest singular matrix with a given sparsity structure, nearest singular matrix polynomial, approximate GCD and nearest unstable matrix. -- --Federico Poloni Dipartimento di Informatica, Università di Pisa https://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

1 1

Short-term Research Associate position @ University of Pisa -- dealii-X project
by Luca Heltai 09 Dec '24

09 Dec '24

Dear all, please share the following information with possible candidates, and to colleagues that may know of possible candidates. Thanks! Luca. Numerical Analysis Group @ University of Pisa Start Date: March 1st Application Deadline: January 24th Application Portal: <https://bandi.unipi.it/public/Bandi/Detail/150eaadb-8fec-4fc5-acb6-593dc7a2…> The University of Pisa invites applications for a short-term Research Associate position within the dealii-X project. This role, based in the Department of Mathematics, will concentrate on Numerical Analysis and the creation of advanced numerical tools for high-performance simulations using the deal.II library. The dealii-X project aims to create an Exascale Framework for Digital Twins of the Human Body. This initiative seeks to enhance personalized medicine through sophisticated computational models, enabling scalable and detailed simulations of human organs. We are looking for dynamic individuals with a strong scientific CV relevant to numerical analysis and simulations (a Master degree in a scientific subject is mandatory, a PhD is a plus). The successful candidate will work on the development and optimization of numerical tools for high-performance simulations in the deal.II library, focusing on meshing techniques, advanced coupling methods, non-matching techniques, reduced order methods, and large scale preconditioning techniques. The role will involve a tight collaboration with other international teams and team members, contributing to the development of the deal.II library. Key information: - Research Focus: Development and optimization of numerical tools for high-performance simulations in the deal.II library - Department of Mathematics, University of Pisa - Numerical Analysis and High Performance Scientific Computing - Contract Duration: 24 months - Gross Annual Salary: €32,427.96 - Application Deadline: 24th January 2025 - Starting Date: 1st March 2025 or as soon as possible thereafter

1 0