Notiziario Scientifico
a cura del Dipartimento di Matematica G. Castelnuovo, Sapienza Università di Roma
Settimana dal 18-05-2020 al 24-05-2020
Lunedì 18 maggio 2020
Ore 14:30, meet.google.com/mwn-midi-gxh,
seminario di Analisi Matematica- AMACA
Luigi Orsina (Dpt Matematica Sapienza Universita' di Roma)
Un sistema di equazioni di tipo Kirchhoff-Schrödinger-Maxwell
Presenterò dei risultati di esistenza e non esistenza, ottenuti in collaborazione con Lucio Boccardo, per un sistema di due equazioni ellittiche, in una delle quali compare un termine non locale.
Lunedì 18 maggio 2020
Ore 14:30, teleconferenza, https://meet.google.com/pip-kvzt-fkz
Seminario delle Meccaniche
Paolo Santini (Università di Roma La Sapienza)
The analytic theory of periodic anomalous waves of the nonlinear Schrodinger model
The focusing Nonlinear Schroedinger (NLS) equation is the simplest model describing the modulation instability (MI) of quasi monochromatic waves in weakly nonlinear media, and MI is considered the main physical mechanism for the appearance of anomalous waves (AWs) in nature. We present the solution, to leading order, of the NLS Cauchy problem for periodic initial perturbations of the unstable background solution, in the case of a finite number of unstable modes, and some of its consequences.
Lunedì 18 maggio 2020
Ore 15:00, meet.google.com/mwn-midi-gxh
seminario di Analisi Matematica--AMACA
Marcello Ponsiglione (Dpt Matematica Sapienza Universita' di Roma)
Limiti di curvature non locali e dei corrispondenti flussi geometrici
In questo seminario introduciamo una nozione di convergenza per curvature non locali che garantisce la convergenza dei corrispondenti flussi geometrici. Forniremo vari esempi ed in particolare caratterizzeremo i casi limite dei moti per curvatura media frazionaria. (In collaborazione con A. Cesaroni, L. De Luca, M. Novaga.)
Martedì 19 maggio 2020
Ore 15:00, ZOOM Meeting ID: 9626126392 Pwd: mdn195, Dipartimento di Matematica, Sapienza Università di Roma
Seminario di Modellistica Differenziale Numerica On-Line
Gerhard Kirsten (Dottorato in Matematica, Bologna)
Order reduction methods for solving large-scale nonlinear differential matrix equations
Nonlinear differential matrix equations generally stem from the semi-discretization on a rectangular grid of nonlinear partial differential equations (PDEs). The two main challenges related to approximating the solution of such matrix equations includes the high computational cost of time integrating the system when the matrices have large dimensions, as well as the cost related to evaluating the time-dependent nonlinear term at each timestep. In this presentation we give a brief overview of how model order reduction (MOR) techniques can be applied to lighten the computational load of approximating these matrix equations. Moreover, we consider in more detail the case where the nonlinear term is a special quadratic matrix function, better known as the differential Riccati equation (DRE). We show that great computational and memory advantages are obtained by order reduction methods onto fully rational Krylov subspaces and we discuss several crucial issues such as efficient
Per informazioni, rivolgersi a: falcone@mat.uniroma1.it
Martedì 19 maggio 2020
Ore 15:45, ZOOM Meeting ID: 9626126392 Pwd: mdn195, Dipartimento di Matematica
Seminario di Modellistica Differenziale Numerica On-Line
Elisa Calzola (Dottorato in Matematica, SAPIENZA)
A second order semi-Lagrangian discretization of the advection-diffusion-reaction equation
Advection-diffusion-reaction equations have a multitude of applications, such as in climate, water and air quality models, or in short and medium range weather forecasting. Due to the potentially very large number of equations of this kind that have to be solved in order to describe such physical processes, every efficiency gain in the numerical discretization used for this very classical problem is of great practical importance. We propose a fully semi-Lagrangian method for the numerical solution of advection-diffusion-reaction equations that employs a second order semi-Lagrangian scheme. Standard interpolation procedures are used for reconstructing the solution in the foot of the characteristics, using both structured and unstructured meshes for the space discretization. We also propose a numerical treatment of Dirichlet boundary conditions. The method allows for large time steps, while avoiding the solution of large linear systems, since it follows an explicit approach. The work is completed by numerical experiments that demonstrate the effectiveness of the proposed approach.
Per informazioni, rivolgersi a: falcone@mat.uniroma1.it
Mercoledì 20 maggio 2020
Ore 14:00, streaming all'indirizzo https://meet.google.com/vsz-nxkm-hav, Dipartimento di Matematica, Sapienza Università di Roma
seminario di Algebra e Geometria
Alexander Lytchak (Universität zu Köln)
Structure of non-positively curved spaces
In the talk I would like to discuss local geometric, analytic and topological structure of spaces with upper curvature bounds and extendible geodesics. The talk will be based on joint work with Koichi Nagano.
Giovedì 21 maggio 2020
Ore 14:00, Il seminario sarà tenuto in modalità telematica, Link per partecipare al seminario: https://meet.google.com/mpv-nitc-sed
Seminari di Ricerca in Didattica della Matematica
Antonio Veredice (Sapienza Università di Roma)
Il principio di induzione tra scuola secondaria e università: criticità e proposte
Giovedì 21 maggio 2020
Ore 17:00, On line Seminar , Web site for information: https://www.dinamici.org/dai-seminar/
DinAmicI: Another Internet Seminar
Martin Leguil (Université Paris-Sud 11 (France))
Some rigidity results for billiards and hyperbolic flows
In a project with P. Bálint, J. De Simoi and V. Kaloshin, we have been studying the inverse problem for a class of open dispersing billiards obtained by removing from the plane a finite number of smooth strictly convex scatterers satisfying a non-eclipse condition. The dynamics of such billiards is hyperbolic (Axiom A), and there is a natural labeling of periodic orbits. We show that it is generically possible, in the analytic category and for billiard tables with two (partial) axial symmetries, to determine completely the geometry of those billiards from the purely dynamical data encoded in their Marked Length Spectrum (lengths of periodic orbits + marking). An important step is the obtention of asymptotic estimates for the Lyapunov exponents of certain periodic points accumulating a reference periodic point, which turn out to be useful in the study of other rigidity problems. In particular, I will explain the results obtained in a joint work with J. De Simoi, K. Vinhage and Y. Yang on the question of entropy rigidity for 3-dimensional Anosov flows and dispersing billiards. Note: The link to the seminar will be posted on https://www.dinamici.org/dai-seminar/ and on https://mathseminars.org/seminar/DinAmicI
Per informazioni, rivolgersi a: sorrentino@mat.uniroma2.it
Venerdì 22 maggio 2020
Ore 14:00, Modalità telematica, Dipartimento di Matematica e Fisica, Università degli Studi RomaTre
Seminario di Logica e Informatica Teorica
Vincenzo Bonifaci (Università degli Studi RomaTre)
The Physarum computer: shortest path problems and beyond
Physarum polycephalum is a slime mold, a simple acellular organism. It was observed in wet lab experiments that this slime mold is able to solve shortest path problems. We consider a mathematical model proposed by biomathematicians for the network dynamics of the slime mold, and discuss how this model solves several nontrivial computational problems. The Physarum computing model yields examples of "natural algorithms", that is, algorithms developed by evolution over millions of years.
Per partecipare al seminario: chiedere il link all’indirizzo email vitomichele.abrusci@uniroma3.it o cliccare sul seguente link https://bit.ly/2Wv8cgh
Venerdì 22 maggio 2020
Ore 14:30, Videoconference talk - visit the ARTS web page and click on the link that you find there., dipartimento di Matematica - Università di Roma "Tor Vergata"
ARTS - Algebra and Representation Theory Seminar
Jorge VITÓRIA (Università di Cagliari)
Quantity vs. size in representation theory
Indecomposable modules over a finite-dimensional algebra R are largely thought of as the building blocks of the module category of R. A famous theorem of Auslander, Fuller-Reiten and Ringel-Tachikawa, states that a finite-dimensional algebra admits only finitely many indecom-posable modules up to isomorphism if and only if every indecomposable module is finite-dimen-sional. This establishes a correlation between quantity (of indecomposable finite-dimensional modules) and size (of indecomposable modules). In this talk, we will take a macroscopic view of the module category and look at certain subcate-gories of modules rather than individual modules. Our focus will be on torsion pairs, which are orthogonal decompositions of the module category. We will show that a finite-dimensional algebra admits only finitely many torsion classes if and only if every torsion class is generated by a finite-dimensional module. Time permitting, I will also make a few comments on how this relation between quantity and size transfers to the derived category of a finite-dimensional algebra. This talk is based on joint works with Lidia Angeleri Hügel, Frederik Marks and David Pauksztello.
Per informazioni, rivolgersi a: gavarini@mat.uniroma2.it
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