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Seminario all'IAC
by torrisi＠iac.rm.cnr.it 21 Jan '20

21 Jan '20

Si comunica che il 30 gennaio 2020 alle ore 14.00 presso l'Aula Riunioni dell'Istituto per le Applicazioni del Calcolo (sede di Roma) si terrà il seguente seminario: Relatore: Professor Alberto Lanconelli (Universita' di Bologna) Titolo: Absolute continuity and Fokker-Planck equation for the law of Wong-Zakai approximations of Ito SDEs Abstract: We investigate the regularity of the law of Wong-Zakai-type approximations for Ito stochastic differential equations. These approximations solve random differential equations where the diffusion coefficient is Wick-multiplied by the smoothed white noise. Using a criterion based on the Malliavin calculus we establish absolute continuity and a Fokker-Planck-type equation solved in the distributional sense by the density. The parabolic smoothing effect typical of the solutions of Ito equations is lacking in this approximated framework; therefore, in order to prove absolute continuity, the initial condition of the random differential equation needs to possess a density itself. -- *Giovanni Luca Torrisi Consiglio Nazionale delle Ricerche, Rome, Italy Homepage: http://www.iac.rm.cnr.it/~torrisi/* * *

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Seminario di Francesco Caravenna a Roma 1
by Faggionato, Alessandra 21 Jan '20

21 Jan '20

Buongiorno Lunedì 27.01 alle 16:00 Francesco Caravenna (Università di Milano-Bicocca) terrà il seguente seminario in Sala di Consiglio del Dipartimento di Matematica La Sapienza. Title: On the two-dimensional KPZ and Stochastic Heat Equation Abstract: We consider the Kardar-Parisi-Zhang equation (KPZ) and the multiplicative Stochastic Heat Equation (SHE) in two space dimensions, driven by with space-time white noise. These singular PDEs are "critical" and lack a solution theory, so it is standard to consider regularized versions of these equations - e.g. convolving the noise with a smooth mollifier - and to investigate the behavior of the regularized solutions when the regularization is removed. Based on joint works with Rongfeng Sun and Nikos Zygouras, we show that these regularized solutions undergo a phase transition as the noise strength is varied on a logarithmic scale, with an explicit critical point. In the sub-critical regime, the regularized solutions of both KPZ and SHE exhibit so-called Edwards-Wilkinson fluctuations, i.e. they converge to the solution of the *additive* Stochastic Heat Equation (after centering and rescaling), with a non-trivial constant on the noise. We finally discuss the critical regime, where many questions are open. Grazie Saluti Alessandra -- ************************************************* Prof. Alessandra Faggionato http://www1.mat.uniroma1.it/~faggionato/ Department of Mathematics University "La Sapienza" Piazzale Aldo Moro, 5 00185 - Rome Office 5, Phone (0039) 06 49913252 *************************************************

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Complexity72h Call for Tutors
by Mateusz Wilinski 19 Jan '20

19 Jan '20

Dear colleagues, We are glad to announce the *third edition of the Complexity72h workshop*, which will take place at LUISS, Rome, Italy, on *July 1-4 2020*, as pre-event of the *NetSci 2020* Conference. Complexity72h is an interdisciplinary workshop whose aim is to bring together young researchers from different fields of complex systems and complex networks. Participants form teams and carry out projects in a three days' time, i.e. 72 hours. The goal of each team is to upload on the arXiv a report of their work by the end of the event. The previous two editions have been a success: 11 out of 11 projects have become arXiv preprints and new collaborations have been born. Each team will have a tutor that: 1. designs and proposes the project; 2. supervises its execution; 3. provides the necessary knowledge and data. *Do you want to become a Complexity72h tutor?* We are opening a *call for tutors* targeting researchers in complex systems and networks. We are looking for people who wish to propose a stimulating project to a team of highly motivated students and postdocs, and have the stamina to carry it out in 72 hours. But is it really possible to do it in just 72 hours? To succeed, we need: 1. A motivated and multidisciplinary team of resilient researchers; 2. A comfortable research environment and supportive staff; 3. A solid and feasible research project and a tutor who can make it happen. We provide the first two. It is up to you to provide the last point. *Send your project proposal (title and abstract) and short CV to: complexity72h [at] gmail [dot] com* , or get in touch with us as soon as possible if you have any questions. *The call for tutors deadline is February 7th, 2020.* Looking forward to your ideas. Complexity72h Organizers

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7th Workshop on Stochastic Methods in Game Theory
by Marco Scarsini 17 Jan '20

17 Jan '20

The 7th Workshop on Stochastic Methods in Game Theory will take place in Erice July 1-8, 2020. https://sites.google.com/view/erice-smgt2020/the-workshop The workshop will include some tutorials that could be particularly useful to graduate students and young researchers. Some slots are still available for contributors who want to present a poster. ******************************************************* Marco Scarsini Dipartimento di Economia e Finanza Luiss Viale Romania 32 00197 Roma, ITALY URL: http://docenti.luiss.it/scarsini/

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avviso di due seminari a Napoli
by Enrica Pirozzi 17 Jan '20

17 Jan '20

-- AVVISO DI SEMINARI DI PROBABILITÀ E STATISTICA MATEMATICA Title: The risk model with stochastic premiums and a multi-layer dividend strategy by Olena Ragulina Faculty of Mechanics and Mathematics, Taras Shevchenko National University of Kyiv Abstract: The lecture is devoted to a generalization of the risk model with stochastic premiums where dividends are paid according to a multi-layer dividend strategy. First of all, we derive piecewise integro-differential equations for the Gerber-Shiu function and the expected discounted dividend payments until ruin. Next, we concentrate on the detailed investigation of the model in the case of exponentially distributed claim and premium sizes and find explicit formulas for the ruin probability as well as for the expected discounted dividend payments. Moreover, we obtain an exponential bound for the ruin probability under certain conditions and study these conditions for some special distributions of claim and premium sizes. Lastly, numerical illustrations for some multi-layer dividend strategies are presented. -- Title: The first-passage time properties of the Jacobi process and applications to neuronal modeling by Giuseppe D'Onofrio Dipartimento di Matematica "Giuseppe Peano", Università di Torino Abstract: Nonlinear dynamical systems are often affected by different sources of noise and the usual belief is that the presence of noise can hinder or deteriorate the signal transmission in the system. However it has been observed, both in theoretical models and experiments, that random fluctuations can sometimes improve information processing. Mathematical models in neuroscience are one of the most prominent examples of phenomena for which the noise is of primary importance or even a part of the signal itself rather than a source of inefficiency and unpredictability. Our aim is to contribute to the discussion on the role of noise, studying the effects of a multiplicative noise on the performance of single neuron models using an analytical approach on the related first-passage-time problem. We consider a model where the evolution of the neuronal membrane depolarization between two consecutive spikes is described by a Jacobi process. We analyze the spiking activity of the neuron under study through the firing rate and the variability of the output related to the first two moments of the random variable first-passage time and we describe the occurrence of a phenomenon of coherence resonance. In particular we present counterintuitive effects due to the presence of the multiplicative noise and its dependence on the input parameters. Based on joint work with Petr Lansky (Czech Academy of Sciences) and Massimiliano Tamborrino (University of Warwick). I seminari si terranno il 23 Gennaio 2020 ore 15:00 e ore 15:45, rispettivamente, in Aula G terzo livello del Dipartimento di Matematica e Applicazioni, Università di Napoli FEDERICO II, Complesso di Monte Sant'Angelo, Via Cintia, Napoli. -- Enrica Pirozzi Dipartimento di Matematica e Applicazioni Universita' di Napoli FEDERICO II Via Cintia, Monte S.Angelo, 80126, NAPOLI, ITALY Tel. 081 675634 https://www.docenti.unina.it/ENRICA.PIROZZI

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Seminario at Scuola Normale Superiore, Tiziano De Angelis, School of Mathematics, The University of Leeds (January 22, 2020, 11:30)
by Giulia Livieri 17 Jan '20

17 Jan '20

Dear all, On Wednesday, 22 January 2020 — at 11:30 — at the Scuola Normale Superiore (Room: Aula Fermi) Dr Tiziano De Angelis (University of Leeds) will hold the following Seminar: Title Probabilistic results concerning smoothness of the value function and of the free boundary in optimal stopping Abstract I will present probabilistic proofs of some regularity properties for the value function of general optimal stopping problems and for the associated optimal boundaries. In particular this talk focuses on C^1 regularity of the value function and Lipschitz continuity of the optimal boundary. Most of our arguments rely on fundamental concepts from the theory of Markov processes and bridge the probabilistic and the analytical strands of the literature on free boundary problems. I will also illustrate situations in which our work improves or complements known facts from PDE theory. (based on https://epubs.siam.org/doi/pdf/10.1137/17M1113709 <https://epubs.siam.org/doi/pdf/10.1137/17M1113709> and https://arxiv.org/abs/1812.04564 <https://arxiv.org/abs/1812.04564>) Feel free to forward this announcement to your colleagues. Best Giulia Livieri

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Seminar Cuturi @Bocconi
by Giacomo Zanella 16 Jan '20

16 Jan '20

We kindly invite you to the following BIDSA seminar: “Differentiable Ranking and Sorting using Optimal Transport” Marco Cuturi (Google Brain / ENSAE) Friday, January 17, 2020 | 12:30 | Room 3-e4-sr03 (third floor) Bocconi University, Via Roentgen 1, Milan Abstract: We propose in this paper proxy operators for ranking and sorting that are differentiable. To do so, we leverage the fact that sorting can be seen as a particular instance of the optimal transport (OT) problem between two univariate uniform probability measures, the first measure being supported on the family of input values of interest, the second supported on a family of increasing target values (e.g. 1,2,...,n if the input array has n elements). Building upon this link, we propose generalized rank and sort operators by considering arbitrary target measures supported on m values, where m can be smaller than n. We recover differentiable algorithms by adding to this generic OT problem an entropic regularization, and approximate its outputs using Sinkhorn iterations. To illustrate the versatility of these operators, we use the soft-rank operator to propose a new classification training loss that is a differentiable proxy of the 0/1 loss. Using the soft-sort operator, we propose a new differentiable loss for trimmed regression. Speaker: Marco Cuturi joined Google Brain, in Paris, in October 2018. He graduated from ENSAE (2001), ENS Cachan (Master MVA, 2002) and holds a PhD in applied maths obtained in 2005 at Ecole des Mines de Paris. He worked as a post-doctoral researcher at the Institute of Statistical Mathematics, Tokyo, between 11/2005 and 3/2007. He worked in the financial industry between 4/2007 and 9/2008. After working at the ORFE department of Princeton University between 02/2009 and 08/2010 as a lecturer, he was at the Graduate School of Informatics of Kyoto University between 9/2010 and 9/2016 as a tenured associate professor from 10/2013. He then joined ENSAE, the french national school for statistics and economics, in 9/2016, where he still teaches. His recent proposal to solve optimal transport using an entropic regularization has re-ignited interest in optimal transport and Wasserstein distances in the machine learning community. His work has recently focused on applying that loss function to problems involving probability distributions, e.g. topic models / dictionary learning for text and images, parametric inference for generative models, regression with a Wasserstein loss and probabilistic embeddings for words. Best regards, Giacomo Zanella Please note: if you are a guest and you do not have a Bocconi ID Card to access to the Bocconi Buildings, please communicate your participation by sending an email to c.monetti(a)unibocconi.it

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Ernesto De Vito @ Roma Tor Vergata
by Anna Vidotto 16 Jan '20

16 Jan '20

Dear all, I would like to announce the following talk that will be held on Thursday January 23rd 2020, at 4:30 PM, in Aula D’Antoni of the Department of Mathematics, University of Rome Tor Vergata. Speaker: Ernesto De Vito Title: Multi-Scale Vector Quantization with Reconstruction Trees Abstract: The aim of vector quantization is a parsimonious reconstruction of unsupervised data as provided by K-means and geometric multi-resolution analysis, to name a few. In the talk I will present a multi-scale algorithm for vector quantization and study its statistical properties. The proposed approach is inspired by decision trees and is based a family of given partitions, to quickly explore the data in a coarse to fine-multi-scale-fashion. The main technical contribution is an analysis of the expected distortion achieved by the proposed algorithm. Both asymptotic and finite sample results are derived. The presentation is based on a joint work with E. Cecini and L. Rosasco. Kind regards --------- Anna Vidotto PostDoc Researcher Dipartimento di Matematica Università degli Studi di Roma Tor Vergata https://sites.google.com/view/annavidotto

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seminario Djehiche a Milano 27/1/2020
by Marco Alessandro Fuhrman 15 Jan '20

15 Jan '20

Il prof. Boualem Djehiche (KTH Stockholm) terrà un seminario dal titolo On a class of mean-field reflected backward stochastic differential equations and the related obstacle problem. Il seminario è fissato alle ore 10:30 del 27/1/2020 presso il Dipartimento di Matematica dell'Università di Milano (via Saldini 50), in aula C (II piano). Tutti gli interessati sono cordialmente invitati. Un sommario è riportato sotto. Il prof. Djehiche è ospite del Dipartimento per tutta la settimana. Cordialmente, Marco Fuhrman --------------------------- Abstract. In this talk I will review some recent results on the solvability of a class of reflected backward stochastic differential equations (BSDEs) (driven by the Brownian motion) of mean-field type, where the mean-field interaction in terms of the distribution of the Y-component of the solution enters both the driver and the lower obstacle. When the reflected BSDE is driven by an underlying Markov diffusion, it is possible to derive a related obstacle problem in the form of a variational inequality involving differential operators w.r.t. both the space and the probability measure components. -------------------------- <signaturebeforequotedtext></signaturebeforequotedtext><signatureafterquotedtext></signatureafterquotedtext>

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Post-doctoral position in probability - Paris
by Cristina TONINELLI 14 Jan '20

14 Jan '20

Dear friends and colleagues, I am currently advertising a post-doctoral position in Probability at Ceremade, University Paris Dauphine. The position is for two years. The expected starting date is September 2020, though a different date may be arranged. The position is funded by my European project MALIG, whose aim is to develop a mathematical approach to the liquid-glass transition and related phenomena. Main areas of research include interacting particle systems, bootstrap percolation cellular automata and glassy dynamics. The successful candidate will also have the opportunity to collaborate with the probability group of University Roma Tre, in particular with Fabio Martinelli, a key member of the MALIG team. The grant will provide substantial fundings to cover working periods in Rome. There are no teaching duties associated to the position. Candidates can contact me directly for any additional informations. Applications including a CV, a list of publications and a one-page description of research interests and experience should be sent directly to me at toninelli(a)ceremade.dauphine.fr<mailto:toninelli@ceremade.dauphine.fr> Applicants should also arrange for up to three letters of recommendation to be sent to the same address. The deadline for applications is Monday, 3rd February 2020. I would be grateful if you could bring this announcement to the attention of potential candidates and distribute it via local mailing lists. Best wishes, Cristina Toninelli --------------------------------------------------------------------------------------------- Cristina Toninelli Postal Address: Ceremade Univ.Paris Dauphine Place du Marechal de Lattre de Tassigny 75775 Paris Cedex 16 - France Office: B617 --------------------------------------------------------------------------------------------

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