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Seminario CN1-SPOKE 10 (Quantum Computing) today
by Gianna M. Del Corso 11 Mar '24

11 Mar '24

Dear All, As part of the CN1-SPOKE 10 on Quantum Computing, we are organizing a weekly seminar series. This week’s seminar is: Title: Hybrid Variational Algorithms for Classical and Quantum Complex Systems Speaker: Elisa Ercolessi (University of Bologna) Venue: Sala Galilei, room 131 ground floor, Bldg C (Dipartimento di Fisica) Time: Monday, 11/03/2024, 17:00 Abstract: Quantum Computing is seen as a potential breakthrough for the study of hard classical problems as well as for quantum many body systems. However, we are in the era of NISQ devices and still far away from fault-tolerant machines. This leads us to consider the possibility of hybrid classical-quantum protocols of variational type: they exploit quantum resources to efficiently prepare states that depend on a suitable chosen set of variational parameters, which can then be determined by means of optimization algorithms to be run on a classical computer. The choice of such classical optimizer schemes is to be guided by compatibility requirements with respect to current available quantum platforms. To evaluate the feasibility of such an approach, we present different applications of the Quantum Approximate Optimization Algorithm to both classical and quantum systems implemented by means of emulations of the full protocol on a classical hardware as well as a case study that has been run on a real Rydberg atom quantum machine. Everyone is welcome! Gianna @@@@@@@@@@@@@@@@@ Gianna M. Del Corso, PhD Dipartimento di Informatica, Università di Pisa Largo Pontecorvo, 3 56127 Pisa, Italy ph. +39-050-2213118 @@@@@@@@@@@@@@@@@

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seminar by Puya Latafat on Tue 27
by Giancarlo Bigi 26 Feb '24

26 Feb '24

You are very welcome to attend the seminar below Best wishes Giancarlo ============ _/Time/_: Tuesday 27 February, 11:00 am _/Place/_: Sala Seminari Est, Dipartimento di Informatica /_Speaker_/: Puya Latafat, KU Leuven /_Title_: / Convergence of operator splitting methods for nonmonotone inclusions /_Abstract_/ Despite their popularity, convergence results of splitting methods have been largely limited to the convex/monotone setting. We present convergence results for several first-order methods, including the proximal point method, forward-backward-forward splitting, and Douglas-Rachford splitting, within a nonmonotone setting. To this end, we focus on a problem class characterized by an oblique weak Minty condition, which captures non-trivial structures as we demonstrate with examples. Moreover, we introduce the concept of semimonotonicity and provide sufficient conditions for the global convergence of splitting techniques for the sum of two semimonotone operators. Illustrative examples demonstrate the wide range of problems our theory is able to cover.

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26/02/2024 - Seminario CN1-SPOKE 10 (Quantum Computing)
by Paola Boito 23 Feb '24

23 Feb '24

Dear all, I am forwarding this seminar announcement on quantum computing, which may be of interest to some of you. Best regards, Paola Boito ============================================================================== Dear All, As part of the CN1-SPOKE 10 on Quantum Computing, we are organizing a* weekly* seminar series. This week’s seminar is: Title: *Quantum Software Engineering* Speakers: *Giuseppe Bisicchia and Antonio Brogi * Venue:* Sala Gerace, Dipartimento di Informatica* Time:* Monday, 26/02/2024, 17:00 * Everyone is welcome! ==============================================================================

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[Indico] Dr Stefano Pozza, How to express the solution of an ODE as a linear system (in a suitable algebra) and exploit it for fast computation., 13/02/2024, 15:00 Europe/Rome
by fabio.durastante＠unipi.it 12 Feb '24

12 Feb '24

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[Indico] Prof. Dario Fasino, Is there a Kemeny’s constant for second-order random walks?, 06/02/2024, 10:00 Europe/Rome
by fabio.durastante＠unipi.it 05 Feb '24

05 Feb '24

Title: Is there a Kemeny’s constant for second-order random walks?, Speaker(s): Prof. Dario Fasino, Università di Udine, Date and time: 6 Feb 2024, 10:00 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Aula Magna). Address: Largo Bruno Pontecorvo, 5 – 56127 Pisa You can access the full event here: https://events.dm.unipi.it/e/258 Abstract -------- Kemeny's constant is a measure of the navigability of a network by ordinary random walks, which appears in a famous result on Markov chains known as the Random Target Lemma. A second-order random walk is a random walk where the transition probabilities depend on two past states. It can be turned into a Markov chain by lifting the state space from the nodes to the directed edges of the graph. The corresponding Kemeny constant is well known but says very little about the second-order walk on the original network. We extend certain definitions and results on standard random walk's mean hitting and return times to the second-order case and provide simple formulas that allow us to compute these numbers by solving suitable systems of linear equations. New results show that there is an infinite family of graphs for which certain second-order random walks, including the best-known non-backtracking random walk, satisfy a precise second-order counterpart of the Random Target Lemma. So, in summary, the answer to the question in the title is: Yes, sometimes. -- Indico :: Email Notifier https://events.dm.unipi.it/e/258

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[Indico] Prof. Dario Fasino, Is there a Kemeny’s constant for second-order random walks?, 2/6/24, 10:00 AM Europe/Rome
by fabio.durastante＠unipi.it 02 Feb '24

02 Feb '24

Title: Is there a Kemeny’s constant for second-order random walks?, Speaker(s): Prof. Dario Fasino, Università di Udine, Date and time: Feb 6, 2024, 10:00 AM (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Aula Magna). Address: Largo Bruno Pontecorvo, 5 – 56127 Pisa You can access the full event here: https://events.dm.unipi.it/e/258 Abstract -------- Kemeny's constant is a measure of the navigability of a network by ordinary random walks, which appears in a famous result on Markov chains known as the Random Target Lemma. A second-order random walk is a random walk where the transition probabilities depend on two past states. It can be turned into a Markov chain by lifting the state space from the nodes to the directed edges of the graph. The corresponding Kemeny constant is well known but says very little about the second-order walk on the original network. We extend certain definitions and results on standard random walk's mean hitting and return times to the second-order case and provide simple formulas that allow us to compute these numbers by solving suitable systems of linear equations. New results show that there is an infinite family of graphs for which certain second-order random walks, including the best-known non-backtracking random walk, satisfy a precise second-order counterpart of the Random Target Lemma. So, in summary, the answer to the question in the title is: Yes, sometimes. -- Indico :: Email Notifier https://events.dm.unipi.it/e/258

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[Indico] Dr Stefano Pozza, How to express the solution of an ODE as a linear system (in a suitable algebra) and exploit it for fast computation., 2/13/24, 3:00 PM Europe/Rome
by fabio.durastante＠unipi.it 25 Jan '24

25 Jan '24

Title: How to express the solution of an ODE as a linear system (in a suitable algebra) and exploit it for fast computation., Speaker(s): Dr Stefano Pozza, Charles University, Date and time: Feb 13, 2024, 3:00 PM (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Scuola Normale Superiore (Aula Mancini). Address: P.za dei Cavalieri, 7, 56126 Pisa PI You can access the full event here: https://events.dm.unipi.it/e/254 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. -- Indico :: Email Notifier https://events.dm.unipi.it/e/254

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Posizione tenure-track (RTT) al dipartimento di informatica
by Federico Poloni 24 Jan '24

24 Jan '24

Buongiorno, segnalo che è uscito il bando per una posizione RTT in analisi numerica (MAT/08) al dipartimento di informatica. Bando e istruzioni per fare domanda sono disponibili su https://bandi.unipi.it/public/Bandi/Detail/b34b7404-9d5a-4180-81e2-bd461bfe… . La scadenza per le domande è il 23 febbraio alle 13:00. La posizione è riservata a coloro che hanno trascorso un periodo di almeno 36 mesi in incarichi di ricerca o corsi di dottorato /al di fuori/ dell'università di Pisa. Tutti gli interessati sono invitati a partecipare! -- --Federico Poloni Dipartimento di Informatica, Università di Pisa https://www.di.unipi.it/~fpoloni/ tel:+39-050-2213143

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Fwd: I: 'TENORS' Marie Sklodowska Curie Network -- PhD positions available
by Paola Boito 27 Dec '23

27 Dec '23

Dear all, I would like to share this message from Iacopo Carusotto (iacopo.carusotto(a)unitn.it), in case someone you know is interested in the PhD positions advertised below. Best wishes, Paola Boito --------------------------------------------------- TENORS (*T*ensor mod*E*li*N*g, ge*O*met*R*y and optimi*S*ation) is a Marie Skłodowska-Curie Doctoral Network / Joint Doctorate (2024-2027), offering * * * 15 PhD positions.* The objective of TENORS is to conduct advanced research that addresses critical challenges in the fields of *tensor modeling and computation*, joining forces from *algebraic geometry, global optimisation, numerical computation, high performance computing, data science, quantum physics.* It aims to feed an innovative and ambitious *joint-PhD program* to train highly qualified young scientists in new scientific and technological knowledge. The PhD candidates will obtain joint/double PhD diplomas from reputed universities within TENORS project. For more information on TENORS see http://tenors-network.eu/ <http://tenors-network.eu/> Application deadline: March 31st, 2024. How to apply: https://project.inria.fr/tenors/phd-positions/ <https://project.inria.fr/tenors/phd-positions/> Where to submit your application: https://easychair.org/my/conference?conf=tenors2427 <https://easychair.org/my/conference?conf=tenors2427>

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Seminario PYSANUM Alessandro Filippo
by Nikita DENISKIN 11 Dec '23

11 Dec '23

Carǝ tuttǝ, Vi segnalo che domani *12 dicembre* alle ore *16:00* ci sarà un seminario tenuto da Alessandro Filippo (Roma Tor Vergata) in *Aula Seminari*. I seminari PYSANUM sono dei seminari informali di analisi numerica e matematica applicata rivolti a studenti, organizzati da alcuni dottorandi Unipi e SNS, con l'obiettivo di presentare in maniera accessibile argomenti di ricerca di analisi numerica ad un pubblico studentesco. Si possono trovare ulteriori informazioni sul nostro sito <https://pysanum.dm.unipi.it/>. A presto, Nikita ----- Titolo: *"Reti complesse: Robustezza, indici di centralità e nuove strategie per il ranking dei nodi"* Abstract: Determinare quali siano i nodi più importanti in una rete complessa è uno dei problemi principali dell’analisi delle reti. Tale problema, anche noto come il problema del ranking, viene tipicamente risolto attraverso il calcolo delle misure di centralità. Tuttavia, cambiamenti strutturali improvvisi, quali la rimozione di alcuni nodi o archi, possono invalidare la nostra conoscenza dei nodi più critici. Per esempio, nodi dapprima cruciali potrebbero perdere tutta la loro importanza qualora rimanessero isolati. Quindi, per studiare l’impatto della rimozione dei nodi più influenti da una rete, sarebbe necessario ricalcolare costantemente le misure di centralità, un’operazione spesso impraticabile per reti di grandi dimensioni. Al contrario, evitare del tutto il ricalcolo potrebbe fornire una rappresentazione della realtà poco accurata. In questo talk illustrerò due nuove strategie per ridurre il costo computazionale del calcolo sequenziale delle centralità, fornendo giustificazioni teoriche a supporto. Infine, mostrerò come sia possibile impiegare queste strategie per valutare la robustezza di una rete ad attacchi mirati. Tratto da un lavoro in collaborazione con Daniele Bertaccini. D. Bertaccini, A. Filippo. *A proposal for ranking through selective computation of centrality measures*. PLOS ONE, 18, 2023.

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